No display but backlight works

So I had a old Iphone 6 plus that was broke and I finally got around to trying to fix it up. The screen was shattered and the battery was dead, so I ordered both a new screen (full assembly) and a new battery.

After reinstalling both the new screen and battery, The phone’s screen is still black, however there is the full back light shining through and working fine, but there is no image, just a black screen. It is still recognized by Itunes when I plug it into my laptop, and the alarms I had set to go off every morning before it broke STILL WORK. I can not use it at all, which sucks because I got all the parts to try and fix this thing. I do not know what could be the problem, and if anyone has any idea as to what I should do, please reply. Thanks.