iPhone 6 Plus boots to apple logo then disappears leaving backlight on
I recently bought a used iPhone 6 + online. Before buying I checked to make sure it was not iCloud locked, it wasn't water damaged. The phone wasn't blacklisted, and there wasn't even a scratch anywhere. It appeared to be in percent condition. The only thing that was wrong with it was the phone not booting up.
I went ahead a purchased it, and it came. I later hooked it up to my computer and first tried restoring it. I held down the home button and the computer registered that the phone was in recovery mode. It asked me if i wanted to restore, or update. I first tried to restore. So far things seemed to be working well until iCloud finished the first step, and began restoring the phone.
I heard the computer make that noise that meant it had lost connection with my device. The iPhone that had been unresponsive with just the backlight showing, now booted up back up to the apple logo, and froze until I forced restart it.
I also tried to update it. That didn't work either.
Using a cellphone screwdriver kit, I carefully took the screen off and examined everything.
I tried unplugging various things (the screen, the battery,) and tried again to restore or update on iTunes. with them detached.
I have watched many videos, and tried the different ways you can possibly fix this situation:
1) by opening the phone in recovery mode manually by holding the volume button,
2) trying to boot in DFU mode,
3) force restarting,
It is possible it could be some internal component that is damaged. But I have no idea where to look. I've heard replacing the battery can help, the wireless antenna, the proximity sensor, even a chip!
Anyway, I would be very grateful if someone can help me troubleshoot this situation, because I would hate to have to spend a lot of money buying every single thing in there to try to fix it, when it might be something simple.
Is this a good question?