Face ID unavailable after screen repair, then face ID not working.

Installed new iPhone 11 Screen. No issues with repair. When customer picked it up, she said the Face ID was not unlocking the phone. There were no messages stating that Face ID was not working. I was able to add my face to her phone, then cleared Face IDs so she could add her face back. When she had to line up her face in the window an error popped up saying that Face ID was unavailable, try again. Tried a soft reset, even tried another screen…same issue. Sometimes it would allow the Face ID to be set up, but mostly the error message that Face ID was unavailable.

Today, using ZXW Tools, I checked the on board FPC Connectors using diode mode. Everything read normal and no capacitors were burned or knocked off from pry damage. Everything is in place and reading normally. I reassembled and turned back on.

Now I get the error message that Face ID is not working nor is the front facing camera. So, I concluded that the Face ID issue was with the front facing camera module the whole time, but now, for no known reason, the Face ID and Camera don’t work. I tried three other camera modules (knowing that Face ID wouldn’t work) just to see if the camera would work. Nothing. Tested the FPC connectors again, still normal readings. Thoughts?! I bought myself a few days with the customer, but the phone is 256GB, so big bucks to replace. Thanks in advance.