Chosen Solution
Ok I got the phone through a friend, the screen was cracked. Bought a new screen, LCD, digitizer and swapped the home button. When I plug it in, it shows low battery, goes black then flashes the apple logo for a split second then turns black(but I can see the backlight lit up) I’ve left it on the charge all night and nothing has changed. wont do anything at all when I hook it to the computer. Tried holding home and sleep and any other sequence for various time limits(same end result) Tried swapping the battery (no avail) Tried swapping the main circuit board to another working phone, phone wouldn’t turn on ( computer recognized it was a phone but said it needed updated) Tried taking out the battery and soaking the phone in alcohol overnight(same end result)
The battery is usually the weak link but if I understand your troubleshooting correctly, you replaced the battery and put the logic board in a known-good phone. Therefore, I would say it appears to be a logic board problem, most likely the charging circuit. This could have happened during the impact which cracked the screen or it be a coincidental issue. Fake chargers and imitation Lightning cables can damage the charge circuitry. This will require a microsoldering repair and is not DIY.
