Why does my iPhone boot up correctly but then shows a black screen?

Hi guys.

Does anyone have any idea why my iPhone 12 boots up correctly (even shows the Apple logo) but then shows a black screen right after? I can feel haptic feedback, and I get calls and texts without any problems so I know the phone is on, but the screen is just black. The apple logo shows fine so I assume the screen is fine?

I've even tried restoring the phone in recovery and DFU mode, but still having the same issue.

One thing to note: I'm currently missing the Earpiece Speaker Module & Proximity Sensor Flex which is on it's way. Had a faulty unit in the phone so replacing it.

Any help would be much appreciated.

Thank you