Does a damaged proximity sensor cable cause black screen?

I am repairing a phone and it was in bad shape when it came to me. The screen flex cables were visible and the screen was loose from the frame which was still in the phone body. This was putting stress on the cables. I bought the screen replacement without small parts, so this means that the front proximity sensor cable, the one that is transferred to the new screen, is the only one that could be causing the issue that I can think of. The backlight of the screen turns on and the phone communicates with iTunes. Should I order a proximity sensor cable and replace that or a new screen with the small parts?

Thank you.