Sonoff SNZB-02 dropped off the network

I have a small setup with zigbee2mqtt, sonoff zigbee 3.0 usb dongle, 4x Sonoff SNZB-02 and an Ikea tradfri ( ICPSHC24-10EU-IL-1).

The Zigbee network worked well for the first few days after installation. but about 36 hours ago, one of the SNZB-02 (the one in the attic) stopped reporting. Before it dropped off, it reported a lqi of 105 and 100% battery. The Ikea tradfri router is about 6m from the attic device.

I tried removing the battery from the attic device, waited about 30 seconds and put the battery back in. Nothing happened (nothing in the zigbee2mqtt log file, zigbee2mqtt map shows the attic device as not connected even after a refresh).

I enabled join on the Tradfri router (through zigbee2mqtt’s web interface) and pressed the button on the attic device for 5 seconds. The led on the device blinked, and the following was shown in the zigbee2mqtt log:

info  2022-07-23 18:05:10: MQTT publish: topic 'zigbee2mqtt/bridge/event', payload '{"data":{"friendly_name":"Attic","ieee_address":"0x001<snip>d3"},"type":"device_announce"}'

After that nothing in the log (except the other devices reporting in as usual).

I have read SONOFF SNZB-02 ZigBee problem which seems to be a similar problem, except that my device won’t rejoin.

Any ideas on how I can troubleshoot this device?