Proximity not working after multiple replacements

Hi,

I've got iPhone 5s from a client with a proximity sensor issue.

This was actually the first time I was gonna fix a 5s display and while peeling of the sensorflex cable the proximity sensor broke because it was heavily glued to the sensor holder. Well, no problem, we just replace the sensor cable to.

While de-connecting the cooper foil connected to the displays backplate the foil got damaged. You know this type of repair where almost everything goes wrong, well, this is one of those repairs...

After replacing the flex cable with a new one, the earspeaker stops working to. OMG, what's going on here? Allright keep calm and just try another flex. Thankfully the speaker and camera are working :) But the proximity sensor still does not work.

Is it possible that this isn't working because of this damaged cooper foil? I'm not even sure what is does exactly. I thought is was for cooling purposes ore something.

Who has some advice? I'm getting kinda desperate here...

Thanks