Rear/Front camera not working after screen replacement.

So, I bought a broken iPhone X on eBay the dealer said he dropped the phone by accident and the phone just shattered in pieces, the glass was cracked and the screen was cracked and the pixels we’re dead so I couldn’t see anything on the screen. After I realised what I was up against I bought an OLED screen for the phone and moved all the parts to the new screen. Everything worked but when I booted the phone I get a message saying that the FaceID isn’t working and when I open the camera app the camera wont load anything rear and front so I am thinking it’s because the front camera wont activate and so the FaceID wont work, but to be honest I have no idea. I have no idea what I have done wrong and yes before you ask the dealer did say he didn’t change anything on the phone, and before removing the screen I did unplug the battery and yes I have checked both cameras, dot projector, IR camera, Proximity sensor and nothing seems damaged. So I have no idea what I have to do, help will be extremely helpful obviously. :)

Black screen when I open the camera app: