First, try restarting the camera to reset the software. If that doesn't work, try flicking the lens piece; the shutter may be stuck and is closed off completely. You can also try refitting the lens piece onto the camera; it might not be properly aligned. If these quick fixes don't resolve your problem, visit our troubleshooting page on iFixit.com for more solutions: Samsung NX300 Troubleshooting

There is no order for removing the screws. However, we did take note it was the most difficult to remove because of it's placement. It is difficult to get a grip on the camera when attempting to loosen this screw, therefore it is more prone to damage. Keep trying, but don't force the screw out to where the part may become damaged by means listed in the previous comment.

-Victoria

Hello Jun. If you are using the correct screwdriver, there may be a few answers to your question:

The camera screw is stuck:

This happened to the team that did this project, just keep working with the screwdriver until it comes loose.

The camera screw lost threads:

If a screw is screwed in incorrectly, it could be permanently lodged in the camera and you will be unable to open it.

The camera screw head is rounded:

If the small pieces of the head (visible) part of the screw are gone with groove marks, the screw is permanently damaged and cannot be removed unless you have special equipment.

Other than these tips, you may need to look elsewhere for more help.

-Victoria