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Display screen will not turn on, is cracked, or is displaying things that it should not be

When you turn on the Chromebook, and you can visibly see or hear that it has turned on, but you cannot see anything on the screen, or something that is not expected such as cracks or strange colors on the display.

Cracked Display

There are visible cracks in the screen or what looks like tearing across the screen with triangular shapes of different colors exasperated by black lines or pools of black. To fix this issue you will need to install a new screen. The easiest way to do this is to purchase an entire top bezel that includes a new screen. Doing it this way will prevent damage to the clips that hold the bezel flush to the screen. While they are not exactly needed to keep the screen protected or anything they do offer protection from dirt and other foreign objects entering the area behind the screen. In order to replace the bezel you are going to have to remove the underside chassis to the C720. This is the black piece on the bottom. The part that you set on the table during use. Then remove the motherboard, and then the screws that hold the bezel in place.

Display is artifacting or displaying strange shapes and colors

This can usually be isolated to an inverter or display issue if the problem goes away by moving the display towards open or closed positions to a certain angle. If this fixes the problem even momentarily most likely there is a cable loose. You will need to ensure that the cables behind the display are securely in place and that the cable for the display is securely fastened to the motherboard. You may not actually need to replace the display or inverter if this was the problem. There is a possibility that the display inverter has gone failed, and needs to be replaced. This particular display unfortunately does not allow for inverter replacement easily, and often times results in further damage. Follow the steps given in the cracked display section above.

The display has dead pixels

On the display you see dots of light of some color that appear to be stuck on the screen no matter what you do. You can try one of the various online tools to resolve this issue by brute forcing the pixels to become 'unstuck', but these are unreliable, and usually ends up in the screen having to be replaced. The good news is that dead pixels are fairly common and do not necessarily mean the screen is dying. So as long as it does not bother you it can be left alone.

The display is completely black or is very dark

This could be due to a few different things. If you cannot see anything on the screen and it is completely dark then it most likely is that the display has failed in some way or a lesser likely cause that a connection has come loose, and needs to be replaced. If the screen is very dark it is possible that you have set the screen brightness to it's lowest setting. Just double check that this is not the issue before continuing. If you have done that and you can see something on the screen, but just barely and under the correct light then most the issue is most commonly that the backlight has failed and needs to be replaced. For simplicity the backlight is to be replaced with the entire display itself. It is very easy to crack the screen if it was not already when attempting to replace the backlight. Follow the steps taken for the cracked display above. As this is the same procedure since the backlight is included in the assembly.

Chromebook will not turn on

"The Chromebook does not appear to turn on. Either with the power supply connected or not."

Chromebook will not turn on at all.

The Chromebook is plugged in using the original power supply, and the power button has been pressed but the lights on the front right of the Chromebook is not illuminated, and there is no audible fan. Before jumping into more expensive and time consuming possible resolutions make sure that the power supply is not faulty. Try another power supply or wall outlet. If neither of those resolved the issue then it is most likely the DC-in.

DC-in has a lot of play in it, or is very easy to move around

The area where the power supply is inserted into the Chromebook is easily moved around or has completely come loose. It may or may not still charge. This is most likely that your DC-in has broken away from the motherboard and needs to be replaced.

Will not charge, and will not indicate that it is charging when the power supply is connected

No matter what you have done the Chromebook will not charge. First isolate that it is not the power supply itself before considering replacing the DC-in. Try a new charger and wall outlet before trying more expensive and time consuming solutions. If the DC-in is able to move around easily or smells of burned plastic often times this means it needs to be replaced. Power supplies that have bent cables at angles larger than 30 degrees, frayed or exposed wires should be replaced before causing more severe issues even if they are working perfectly fine. The power supply should also be replaced if you have to physically bend the cable to get it to properly charge (that is you have to actually bend the wire itself not apply pressure to where it plugs into the C720 this indicates another possible issue). If you are moving the cable to press inside of the DC-in this could also indicate that the DC-in needs to be replaced, and not the power supply itself.

Chromebook indicates that it is charging, but the battery will not hold a charge

Even when you have charged the Chromebook overnight or for a few hours it will not hold a charge no matter what you do. This is most likely just that the battery has gone bad. This is normal and happens after a few years of use or in some cases when a device has not been turned on or charged for an extended time.

Keyboard is malfunctioning

"The keyboard is not working as it should."

Keyboard keys are sticking

The keyboard keys stick in the down position after pressing even for just a few moments, or are harder to press than normal. This can be easily resolved in most cases by cleaning off the keyboard area with something like a baby wipe. DO NOT spray anything onto the keyboard. If this did not resolve the issue keyboard replacement may be needed. Spilled drinks on a keyboard can cause it to become sticky or stop working entirely. You will need to replace the keyboard after spilling something on it as a simple wipe will not be able to clean the underside of the keys.

Certain keys or all keys on keyboard are not working

Make sure to check the keyboard connections (requires dis-assembly and access to the keyboard ribbon cable to the motherboard) as sometimes this is due to a loose cable for the keyboard. To check if this was the issue remove the ribbon cable properly to avoid damage, reattach it and re-lock it securely into place. If reconnecting the cable did not resolve the issue then you will need to replace the keyboard.

Errors with the SSD

"You are receiving errors about a missing operating system, there are random system errors even after a re-installation or repair of ChromeOS."

Operating system errors even after system repair

If you had recently re-installed ChromeOS or repaired it, but are still receiving errors from the operating system and not third party software (such as a chrome extension / addon) this can often times be attributed to a bad SSD (or one that is going bad) that needs to be replaced. SSD failure is not too common so I would try and exhaust all other options before going with a replacement. This is most commonly a software issue, and not a hardware issue. If you would like to replace the SSD you will need to remove the motherboard to gain access to it. Then remove the screws that secure it to the motherboard and replace it with the new one.

Operating system not found errors

Most commonly this is something that can be repaired by running a ChromeOS repair. If this does not fix the problem, or if when trying to run a ChromeOS repair you cannot find your drive then it usually means you are going to need to replace the SSD as it has completely failed. If you would like to replace the SSD you will need to remove the motherboard to gain access to it. Then remove the screws that secure it to the motherboard and replace it with the new one.

Miscellaneous issues

"If the solutions above did not answer your questions try these."

A device is not working even after replacement

This issue is a difficult one to diagnose, and usually should be considered a last resort for numerous reasons such as cost. The motherboard on the C720 controls almost every aspect of the Chromebook entirely as they are soldered on. The RAM, Graphics Card, CPU, Various Buses, Chipset, Firmware, BIOS, and much more. These are all things that can cause failures of the computer and their respective components. For example if you have purchased a new SSD and used the replacement guide, and are 100% sure that the one you received is in full working condition, but it still will not work it can in more extreme cases be attributed to the SATA controller being faulty on the motherboard and most likely not the drive itself. Sometimes even harder to predict problems such as frequent SSD failure due to the incorrect voltages being sent through the drive causing it to fail prematurely. This could be due to a bad SATA controller, a short somewhere on the board, or a faulty power supply. If you still feel that your motherboard needs to be replaced or you have just given up entirely on replacing things piece by piece replacing the motherboard is usually the cure all for this Chromebook since replacing it will replace so many other components simultaneously. To do so follow this guide.

Graphics (video) card is not working or displaying strange shapes and colors on screen

If you are seeing strange shapes on the display usually during intense computations such as when playing video games or watching videos versus a constant issue it might be that the graphical unit of your Chromebook needs to be replaced. Make sure that it is not the display or it's inverter that are actually causing this issue as you are going to have to replace the motherboard to fix it as it is soldered onto the motherboard and cannot be removed with a normal soldering iron. You can do so by following this guide.

RAM module is bad or has failed

Random system restarts, program crashes, or errors that the memory is bad either with a program for testing or within ChromeOS directly can all indicate that the memory modules need to be replaced. Make sure to test the modules before actually going to replace them. Unlike many other devices the memory is not easily replaced on the C720. You will have to replace the motherboard entirely since the memory module is soldered onto the board itself and it requires expensive equipment to desolder and resolder. It cannot be done with a conventional soldering iron. Follow this guide to replace the motherboard. An easy way to tell if the RAM module is bad is if you hear three one second beeps one after another followed by a short pause when turning on the Chromebook. There are many different beeps that could indicate something else, but this one is meant for bad memory. Which could mean a module is loose or something else, but since it is soldered on to the motherboard we can isolate it to being a bad module since it will never come loose (or shouldn't). In addition to the beeps the display will not turn on.

Chromebook randomly shuts down even when plugged in

This can be due to a few different things. It could be a: system error, bad memory module, failing SSD, thermal issues, power supply or battery, or even the motherboard itself. The cause is usually easy to isolate. To start most of the time it is just a thermal issue. Usually thermal issues are contributed to poor airflow which can be resolved by replacing a fan or something as simple as a dusting. A good way to tell that the fan needs to be replaced is by a rattling sound coming from the Chromebook. System errors can be fixed by running a repair on ChromeOS in most cases. Power supplies and batteries can cause random shutdowns if the power supply is connecting and disconnecting frequently due to either the power supply being bad or the DC-in. The power supply can also be an issue if it is giving the incorrect voltages to the Chromebook which can cause a slew of issues that can either destroy every electrical component inside of the Chromebook in one swift movement or slowly take them all out one by one. A bad SSD can sometimes attribute to frequent restarts, but these will usually be masked as system errors. If you have repaired the system several times and it continues to fail consider replacing the SSD. The motherboard itself can be the issue, but due to any number of things. The cheapest is something is causing the board to short such as a loose screw connecting two traces that should not be connected or a cable has frayed. These are both not likely, but possible. If you have replaced everything else or are completely unable to isolate the problem consider following this guide for replacing the motherboard.

Chromebook shuts down after running for about five minutes, or when I play a game or am watching a movie

This is most likely due to a thermal issue, and can be resolved by either dusting out the unit by removing the underside bezel and dusting the components with an air can designed for electronics, or/and replacing the fan. Fans often collect hair, lint, and tar buildup from cigarette smoke causing the fan to have to work harder to move the same amount of air as it was when the C720 was new until the passage is too clogged to operate effectively. In more severe cases the fan can be taken apart to clean with a soft brush or better spraying with an air duster.

Back to Device Page

replaced new screen , now wont start up unles i put power cable in ?

robert francis - Antwort

If you replaced the screen and now the device won’t start, it is possible that the power-on-self test (POST) is not detecting the screen (check screen connection), or that the battery has a faulty connection (check battery connection) or is completely used-up (buy a new battery).

gillies -

Using 。USB to detect

Ryan Bettis - Antwort

Marvelous to using

Ryan Bettis - Antwort

I have a fleet of these at a school. In my experience the most common causes of not charging are:

1. Bad battery ($15 on ebay) (careful when removing; the bad ones are often inflated and can burst into flame if punctured)

2. Bad power jack (usually easy to solder back into place if you're into that. Often the center pin has fallen out of the jack entirely and is sitting in the case somewhere.

3. There is a little black momentary switch next to the hinge closest to the power jack. This switch seems designed to cut out the battery charging circuit when the bottom case is off. However, sometimes the switch fails to get depressed far enough by the case even when it's on. The switch can be either soldered short, glued down (pro tip: baking powder catalyzes superglue), or some kind of shim can be added to the case to depress it.

Adam Alexander - Antwort

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