Motion detector shoeing tampered message on app

Hi. I have 2nd generation system that i installed in my house. I have 3 motion detectors, 2 contact sensors, camera and bell. All seem to work fine except one of the motion detectors. It keeps on giving a tampered message. I tried to remove it from network and add it again as well as do a complete reset and add it again but eh tampered message does not go away. Can someone please help on any steps to remove the tampered message ? Kind regards Amol.