Mac hardware repair.
Answer to: Flashing question mark; after reboot no keyboard and trackpadHold down CMD+V and if it stopped loading, get the log file where it stopped. That is the easiest way to diagnose without special tools. It is called verbose mode. The suspicion is the I/O cable may be loose or do not have good contact point or the Broadcom card is failing soon.
Answer to: Had no backlight. Replaced Backlight Driver and now NO POWERFirst of all, no backlight doesn't mean the backlight driver only. There is backlight switch, sensors, current controllers, coils and booster all need to accounted for the backlight. Why the backlight driver was bad? Which component was shorting the power ? what about the pads? Have you double check the driver orientation> Seem like YT videos seem to be easy jobs but in reality. So you need to back trace from the orientation of the chip first.
Answer to: During Use, MacBook Pro Screen Goes Black - HELP!?By the way, per your post, it is more to mid 2012 MBP retina. The symptoms are similar to the drive health. Hold down CMD+S at start up to get to single user mode wait until it finished loading and press enter then type the following fsck -fy >>>Enter It will check the drives and when done try another one Try this command for a few different times with different volumes fsck_hfs -r /dev/disk1 then enter or disk1s1 or disk0s2 what ever depend on your drive partition. That should make a lot of different. If that is not a solution, the EFI firmware need to clean up. It may have some address issues. The device should be fine but the drive directory may corrupt. If it is EFI firmware, it cost $120 to reflash plus shipping. (lol good marketing) Update (06/05/2018): Power up the device while holding the Command + S until the command lines appears. Then press enter once and type the following line to make so many feel comfortable. fsck -fy The internal drive is usually disk0 and use the volume directory to rebuild ea...