lcd flicker and white and black lines

Hey guys!

So I just recently did a complete tear down on an iPad Air 2 and put it back together on a new housing (the old one was completely bent) the screen was also broken but you where still able to use it. After I put all of the iPad Air 2 together on the new housing I hooked up the old screen to see if everything was working probably (altought of course I am going to put a new screen on it I just wanted to make sure everything was running smooth first) i plugged it in to the charger and what I got was a black screen and a tiny constants flekering light and finally a white screen with a black strip down the middle of it. I checked the FPC conector to see if it was intact and it is (thank God!!) so I’m not sure what could be causing it to do that?