I’m happy to hear you got everything working. Regarding erroneously reconnecting in Firmware Update mode – this is due to an Android bug where it caches the services offered by a BLE device and doesn’t clear the cache even when those services change. So Android was remembering the Firmware Update services and not showing the Metering services to the app. This is why a phone reboot fixed that problem.
If you’re interested in reading more about the problem you can see it here:
Let me know if you have other questions, best