Chosen Solution
Have replaced power button cable, rear camera lens(that annoying part in the back, used super glue), rear camera, and screen. Turned the phone on once the work was done and everything proved fully functional. Turned it back off and stored it for 2 weeks(May have turned it on again a few times in between that time to take pictures of it but can’t recall when exactly). Will now not turn on. Have attempted to replace battery, plugging it to pc, trying to turn on without the screen or only a few cables seated, no result. Completely dead. The device has been pretty much stationary with no use under my desk the whole time. Ghosts in my house came for this phone, perhaps?
Not ghosts…but these guys ;>) If using only a known-good battery and Lightning port connected to the logic board and the phone still won’t boot, then the problem is logic board related. You could start probing the logic board, if you’re so inclined. Start with the main power rails (PP_BATT_VCC, PP_VCC_MAIN and PP5V0_USB) to see if they are shorted to ground. Let me know and I can provide more steps. Otherwise, you may want to consider having this looked at by a micro-solderer.
