Changed 7+ camera lens, now rear facing cameras not working right?

I changed the rear facing camera glass with the metal piece attached. Upon completion, I checked the cameras and only the front facing camera worked in the camera app. Opening Snapchat though, the standard camera (not 2x) works as well as front camera still. But back to the camera app, it does not work. I tried a new camera flex, removing the padded metal ring, applying electric tape to the metal components possibly touching PCB. Only for a brief period (after removing padded ring, but before applying electric tape), it worked, until I closed the phone, where the problem came back. Also the flash still works, but only if the camera app hasn't been opened or is closed.