Moto X Play XT1563 Will not turn on after LCD replacement
Had a broken LCD in this Moto X Play XT1563, ordered a replacement screen and installed it (I have 5 years experience as full time technician) everything went smooth, careful battery removal, no damaged flex cables or broken IC's on the board. Confirmed all components are in perfect condition with a microscope and meter-checked the battery, reading 4.20 V, full charge.
PROBLEM: When trying to power on the phone it displays just a large battery symbol/logo with an exclamation point/mark on it for about 3 seconds and goes black again. This tells me that my LCD is functioning because it displays an image, but the phone fails to turn on.
All battery terminal connectors are soldered and in perfect condition, after pushing the power button and the battery icon is displayed, the voltage drops from 4.20 to 4.17 which seems normal and should not prevent the phone from turning on. The phone worked before disassembly but with busted/blank LCD, I tried booting the phone with the original destroyed part and it seems to be doing the same thing. Plugging in the charger makes no difference, for as long as it's plugged in, it just cycles between blank/off and the battery/exclamation.
Any ideas what could be causing this issue and what I could try to get this phone working again? Is there some sort of volume key combo I need to do to recalibrate the battery after removal?
Is this a good question?