Motion Detector False Alarms

I just installed a 2nd gen ring alarm system. Everything seems to be working as it should except the motion detector. It false alarms every couple of minutes when set for high detection, every five or ten minutes on medium, less often on low. I followed installation recommendations, nothing in the room that moves, no drapes, no pets, sensor nowhere near a window, heater vent, etc. I have factory reset the sensor, still same problem. Removed from system and reinstalled twice, no luck. The sensor detects legitimate movement. Looks to me like it's defective, but since I purchased a bundle from Amazon there does not appear anyway for me to return it. So, is it broke???