If it was made for the same Mac model, for example, MacBook Pro (12,1) then it will be compatible with all MacBooks. If the logic board from 2013 was made for the model of Mac that you have, it should work fine with your MacBook. Good luck fixing your MacBook Pro!

I think it may well be one of the cables for the keyboard and trackpad. If the cable seemed broken when you ordered the replacement part, then it very well could have caused the keyboard backlight to break too, as they could be shared from the same cable. You might also want to check all other cables to make sure that the keyboard cable is looking fine. If the replacement cable does not fix these issues, the the problem may well be something else. Good luck fixing your MacBook Air!

Theoretically, yes. If the connectors are the same, which I am pretty sure they are, then you should be able to get video on to the display. I think I have also seen this be done in a video before, but I can't recall the video. Looking at pictures of both panels, they seem to have the same connector. EDIT: Doing some further reaserch, it seems, that yes, it can be done, as people have swapped them on 2012 models for anti-glare displays.

Can you try disconnecting the battery and seeing if it will boot normally? This way we can rule out weather it will be a logic board or battery issue. If it does boot normally, great! It will most likely be a battery issue. Otherwise we will have to look further into this. You could also try reseting PRAM, by powering off your Mac, then press your Mac's power button and then hold ⌘ + option + P + R, until the boot chime plays. If you do hear the boot chime then, then you will know that it is most likely working, and continue to boot up the Mac. You could also try booting into safe mode, to rule out if it is a software issue, but it sounds less likely. You can do this by booting up your mac and immediately holding shift: https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac#:~:text=Turn%20on%20or%20res....

iFixit does not sell all parts for all devices. I am pretty sure that they do not sell this spesific battery for this computer, however, Dell does. You can find the OEM battery for the computer here: https://www.dell.com/en-us/shop/pfydresults/275206 You may be able to find 3rd party batteries, or used batteries for way cheaper, but the safest option is to buy from Dell, as they made the computer, so they should have the best support and quality. Hope this answers your question!

Have you tried to see weather it works plugged in to power? (If you can do this with the camera, of course) After doing some research, Error 99 seems to mostly have to do with the shutter. (Error99 basically means there is a problem with the camera, but the device is not sure what the error is) Try to see if you can lock up the shutter for cleaning. If that does not work, then you might want to try to further investigate the shutter. Good luck fixing your camera!

I think that buying a replacement screen might be your only option... You might be able to find an IC locked iPhone XS max, and use the screen from that, but that option is only sometimes cheeper. You might also want to remove the screen to see if it is a display data cable, but this is most likely not the case, as they are screwed down under brackets. EDIT: I found an XS Max replacement screen on Amazon for only 40 bucks.

It might not be the motherboard. You might want to replace the thermal paste in the device. Follow this guide, and then install new thermal paste onto the die of the heatsink Microsoft Surface Laptop 4 (13.5-inch) Heatsink and Fan Replacement Make sure not to strip any screws, as that could cause the heatsink to not have direct contact with the CPU. You will also want to be very carefull applying thermal paste, and make sure to cover the whole die, and not to scratch it. Good luck fixing your device!

A grey circle with a slash means that the macOS is not compatable with your mac. https://support.apple.com/en-us/101666 To solve this, you may want to go into recovery mode, by holding CMD and R at the same time. https://support.apple.com/guide/mac-help/use-macos-recovery-on-an-intel-based-mac-mchl338cf9a8/mac#:~:text=Restart%20your%.... If no hard drives show up in recovery mode, then the hard drive is broken. If they show up and are functional, the hard drive should be good, and you can continue with a fresh reinstall of macOS.

Did you make sure you assembled everything correctly? If included with the screen, did you add on a watertight seal? Some 3rd party displays do not fit the phone correctly, as I have had an iPhone screen replacement that was too big to fit correctly into the frame of the phone. You may want to buy a replacement screen directly from Google, or the ones supplied from iFixit.