iPhone 5S, only responding to one screen?

I am working on a customers iPhone 5S, which is throwing an extremely weird issue.

Customer came in for a screen replacement, the screen itself is not cracked or damaged, it’s just ‘dark’ and has an Apple Logo burned into the screen which can be see on a white background. The screen the customer originally had on their phone is NOT an original Apple part/screen.

When using a replacement screen (I have tried 3 - 4 screens), there is no picture being shown on any of the screens (phones shows erratic AMP draw, at around 1,5 Amps briefly, before settling into what appears to be a normal AMP draw for booting.) Just no picture on screen. When I reconnect the screen the customer came in with, everything works fine.

Why is this iPhone 5S responding only to ONE screen? Everything is working normally when the first screen is attached, it’s just the picture which is slightly dim.

The phone has had a previous repair attempt(s), I have inspected the board under a microscope, and noticed two capacitors ‘little peckers’ were missing (C23 & C25). I have replaced these two caps, which has not changed anything.

Any help on this weird issue would be greatly appreciated.

Edit: Backlight is working on all screens tested on the phone, just no image. AMP draw on boot is the same, regardless of which screen is connected.