Motion Detector (2nd) keeps tampered msg

Bought the 10 pieces set of alarm and finally got them. All are fine except one of the motion detector keeps have tampered message, while another works fine. No matter I open and close the back cover again and again. And I found the back (without the back cover) of both working and non working detectors, the non-tampered detector has a tiny white spot, while the tampered does not have it. I quite sure it is the cause of tampered message. But due to pandemic situation, I cannot contact any support staff from Ring and I believe that particular detector needs replacement. Pls advise how to do, thx