Front camera doesn't work, display rear camera instead.

While replacing a battery I also disconnected the frontmodule on a iPhone 6 since the adhesive was really stuck on it. After the everything was done and put back into place the front camera didn’t work.

Now when I try to use the front camera it’s either, all black, say the phone is too warm and need to cool down before using the flash or it uses the rear camera (with a new frame every 5 seconds or so).

I tried swapping out the front camera with a new working one but it did not help. Same problems still occured.

Any help would be appreciated!