Blank screen before OS and no camera.

I replaced my screen with something I found on Ebay because my original had a crack in it and likely the flexgate problem as I have to change the angle to get rid of lines sometimes.

The new screen doesn’t work properly.

At first the screen is blank whenever in any of the firmware menus such as the alt key boot menu. Once its booting up with the Apple logo the display is fine but the webcam doesnt work at any stage.

I thought it was a bad screen but I got another from a different supplier and still the same. I even tried that on another mac and it works with that.

I’ve inspected the board and flex cables closely and there are no visible burns or liquid damage. I even swapped the flex cable for the display without any improvement.

I’ve tried updating the firmware on the computer by upgrading to Montery. Fully wiped the drive and reinstalled. I’ve also done all the basic PRAM and SMC resets.

I’m sure the screens I’m getting arent 100% official but they work on another macbook fine and my one works fine with any official screens.

I’ve read that flexgate can cause a short to the CPU on the 13” models but on the 15” (mine) this can damage a mux chip which is reponsible for swapping between intergrated and dedicated graphics. Does this sound related?