samsung galaxy tab e

I have a Samsung galaxy tab e that was unfortunately mistreated by someone which has caused the backlight/LCD screen to light up. It still powers on and works you just can't see the screen. I've watched YouTube videos, taken it apart to make sure all wires and strips are attached with no luck...

Firstly my tablet screen frooze and the writing turned a green colour and lines appeared then it re started, it kept doing it every 2-3 minutes, I tried to look at it in safe mode but that made it worse. Now it comes on to opening screen then switches off, and it's also made a loud screeching...