I purchased a few more contact sensors, and all connected and work just fine except for one. I cannot seem to find a way to connect this sensor and have tried every trouble shooting tactic from removing the battery, to holding the tamper switch etc. I’m not sure what else to do.
I assume you did the factory reset when you spoke of the tamper button?
reboot the base station
for giggles try a different battery.
Then I think you have done all you can do. If it was Amazon just return for replacement