Wear OS watches such as the LG-W280A LG Watch Sport can get stuck in a boot loop under the following conditions, even with a relatively new battery:
- watch cellular on
- watch out of WiFi & Bluetooth range of phone
- watch reboot or power on
- weak cellular signal makes symptoms worse, due to increased watch cellular transmit power
the symptoms of this Wear OS boot loop are:
- OEM logo appears
- Wear OS boot sequence gets most or all of the way through
- the watch will either turn off or reboot before the watch home screen appears. If the cellular signal is a little stronger, you may get into the home screen with stuttering and screen shutting off.
If you get a strong enough cellular signal, you may be able to shut cellular off to allow boot to complete.
This means those looking to use a Wear OS cellular watch like the LG-W280A LG Watch Sport in cellular standalone mode could find themselves stuck in a bootloop while running the watch in cellular mode, away from the phone. Specifically, those looking to use Wear OS in cellular-only modes, like a child riding the bus etc. could be at risk of boot loop. This occurs across several Wear OS versions.
Why bootloop happens
In general, boot time for any device is perhaps the highest power consumption part of the operating modes. when cellular is on with weak cellular signal, out of range of phone Bluetooth and Wifi, the Wear OS watch is simultaneously booting and trying to sync over cellular. This appears to exceed the battery capacity of Wear OS devices such as the LG Watch Sport.
Unfortunately for those needing the watch in an emergency situation, you may only be able to unstick from this boot loop while the watch is on the charger. The other possibility is to get to an area of strong cellular signal and shut cellular off. Or finally, to get within Wifi or phone Bluetooth range.