In order to prevent piracy, each hard drive used by a PS4 is crypted. The key is linked to the motherboard. So if you change your motherboard or your hard drive, you will have to format your drive to use it. Install the new hard drive Download the update. Place the PS4UPDATE.PUP on a USB key in ://PS4/UPDATE (download here official https://www.playstation.com/en-us/support/system-updates/ps4/ Plug the USB key Touch the power button for at least 7 seconds. Select [Initialize PS4 (Reinstall System Software)] Sorry you lost your saves.
You can update your rooted android by doing it manually. Download the firmware or rom you want to install then follow this TUTORIAL. You will surely have to download the latest version of the tools to use instead of those proposed.
An A/C adapter box always do a humming noise since it use some alternative current at 60 Hz or 50 Hz, but it is very descrite and you shouldn't normaly notice it. As you noticed the humming noise(which is not good), try an other A/C adapter box (from a friend,...) or start investing in the A/C adapter box for any short cut, dead fuse, or anything supsect. Be carefull with capacitors in it, make sure they are discharge when working.
You should carefully clean all the connectors and make shure that tey are well clipped. It happened to me on an iPhone4. The + volume button was the only one that was not working, so ... check and clean conections ! Second option ont he same iPhone 4 after a screan change the repair man had to connect and disconnect the iphone to itunes (or maybe a special soft) to make the service back again. He was aware about this sublety and make the service work just after the repair
iFixit is for fixing things, not for this kind of project, but i'll answer you. As you posted this question it is obvious that you didn't made a google ressearch, there are hundreds of well documented tutorials. There are two ways to build a drone : °First you go to a specialised model making shop and just buy parts to assemble together (structure, motors, variators, control board and radio, batteries) °Second solution, have to buid yourself the parts mentionned above. Built the structure with some wood for example, use some microcontrollers and sensors for the control board (or arduino if you are a beginner), use radio tranceiver then finaly code the µC. It takes first a lot of time for designing it and understanding how everything works.