Chosen Solution
Prior to the repair, This iPhone was starting to have battery issues (died quickly and would shut off w/ 10-20% battery). I planned on having Apple replace battery but then it was dropped and screen broke. After that it was not turning on reliably. I replaced the display and battery on the iPhone and it was acting kind of weird before I reassembled it. It wouldn’t always boot but it seemed like if I detached the touchid cable, it would immediately start up. I reseated various cables and then it seemed to be more reliable, however, now that it’s been reassembled, it is shutting off and having a hard time booting back up. Can it be that something w/ touchid would disable the phone from starting up? I’m fine with leaving it unplugged but I’m hoping for some confirmation before cracking it back open. Update (08/27/2018) I’m starting to think it’s this connector
Yes, if the home button extension cable or home button is damaged (look for signs of tears on the cables) they can cause the phone to not boot up or shut down when using it. Does the home button and touch ID work fine? Sometimes the damage on the long cable that runs behind the LCD display metal shield isn’t noticeable until you take it off and look behind it.
