Tag is armed by itself and sends movement notifications when there were no movements

[jbtibor]

Yet another tag went crazy. It arms the movement sensor by itself and starts sending movement notifications. It is attached to a concrete wall so there's definitely no movement.

I disarm in browser, check in Android app that is really disarmed, then after a while is armed again and notifications start. Sometimes is after half day, sometimes 5 minutes after last disarm. What can I do except using a hammer to disarm?