Chosen Solution
I had the phone opened up to swap out the front camara with a new one. Closed it back and the front camera still wasn’t working so I opened the phone back up to put the original camera back in. When I was putting it back together this time I accidentally let the screen fall back 180 degrees (all ribbon cables were connected and plate screwed on at the time). After closing the phone up the screen was black. The phone turns on, receives calls/texts but black screen. It isn’t recognized by itunes however. I have removed all the ribbon cables and put them back multiple times to make sure everything is seated correctly. The battery is always disconnected when working inside the phone. I always put the screws back in the right holes. I even ordered a new screen with the front camera built in and it didn’t help, which also rules out a backlight issue. So I’m assuming the problem is damage to the ribbon cable connectors on the logic board or the logic board itself, which is beyond my ability to repair. Am I missing anything that can be adjusted/repaired aside from having to send it off? The phone is too old to put alot of money into it.
Based on what you say and what you have tried to date, I would closely inspect the connectors on the logic board as they may have been damaged from the stress. The other possibility is the backlight circuit, like @tech_ni suggested. However, that mainly occurs when the battery is not disconnected prior to working on the screen. So start by looking at the connectors, preferably with magnification. Look for damaged pins, plastic or missing or partially dislodged components in the surround area. To test the backlight circuit, shine a bright light on the screen right after connecting it to an iTunes enabled computer. If you see a dim image, then you have a backlight issue. It could be the screen but you have already tried another one so it’s likely a board level problem. Ideally, you want to use known-good parts to troubleshoot.
