I check the received model

There are a lot of references, the model I received is well stamped 19DZT.

I put batteries

This model is equipped with a very practical AAA battery system (not supplied).

I launch the Zigbee pairing

I switch Zigbee2MQTT to pairing mode but nothing happens.

I press the small black reset button on the back until the LED flashes.

The pairing starts.

 

The Open/Closed contact is well-functioning.

Clearly the information on the batteries goes up.

I'm going to Home Assistant.

I can find my equipment there

It is perfectly integrated! Note that it dates back to 19DZT, impeccable.