Solder battery to VCC and GND terminals. I also connected the positive pin of the battery holder to UART_RX but just for a firm attachement of the battery holder. The black wire is connected to the VCC, the other pin is soldered directly to the GND edge connector.

Use UART DFU or J-TAG connector to program the firmware. This is stock "generic-node" firmware from the github without any modifications.

Enable pairing on the gateway, then put the battery to the module and pairing is done.

Connect to the MQTT topic to get the temperature. I use bc-raspbian image from BigCLown Releases on GIT which has pre-installed all the services and Node-RED with Dashboard