New back camera is black

Hi everyone!

I got an iphone 7 in my shop.. the old camera has black spots on it. I have tried canned air, q-tips, isopropanol and a microfiber cloth. Still black spots.

Here is my problem, I have 3 main cameras for iPhone 7 as spares in my shop but they all turn out completely black when I plug them in the phone. I have tried reset all settings, reset (lock button + volume down) and turning the phone on off..

Is it my three cameras that are bad or is the phone damaged?