I had the same problem too. Was the SSD new or was it used on another computer? Because if it was used, you should format it. Or it could be the problem with the 9400M. Because Apple and NVIDIA had an issue with the chip and it would cause it to basically become useless. If its not the SSD, take it to the Apple store and get it checked.
If it came with 3 screws, then it’s an extra one just in case if a replacement screw gets lost.
Yeah it would work, but if the battery heath on the 2nd battery is bad, just get a new one.
Of course! As long as the screen and battery are disconnected from the motherboard, you can replace anything!
My screws are too tight that I can't unscrew it. What should I do?