Backlight on, no display, beeping repeatedly
So basically, I bought a iPhone 6 16GB off of ebay for a good price, mint condition. The seller said the phone screen doesn't turn on after a battery replacement, but it gets recognized by iTunes and so on. Sure thing, I plugged it in, phone turns on and gets recognized by iTunes. The screen didn't turn on though. I decided to buy a new screen and battery, just in case, and just installed both few hours ago. Now the Backlight lights up, which it didn't do before, but still doesn't display anything. Still beeps repeatedly, but only when it's plugged in, otherwise it just stays on. It also only turns on with the cable connected.
I tried disconnecting the screen cables multiple times, unhook the battery and letting it sit for 10 minutes (actually letting it sit right now for another hour) and the usual home + power button thing. Nothing helped so far.
Edit: Now it won't react at all, no vibration or sounds, no backlight, but it's still showing up in iTunes.
I took the phone to a professional and it indeed had long screw damage. He himself though said it was super hard to find, since the previous owner did not do a lot of damage but enough to make my phone not function correctly. 80 bucks later and my phone is working again!
Is this a good question?