Apple Watch boot loop caused by update

The overnight update to my Apple Watch has left it in a boot loop, where it restarts, shows the apple logo for a few seconds, then restarts and repeats. it has done this now for a day and a half.

I’ve attempted to reset it using the crown and side button for 10 seconds, and that achieves nothing. It just starts the boot cycle again. I can’t do anything else with it as it doesn’t make it far enough to allow my phone (11 pro on ios15.6) to interact with it.

Watch worked perfectly fine until the overnight update. it froze during the loading screen, and gave a red exclamation mark. I followed the instructions (open phone, double click side button etc) and the watch then rebooted and has been in the bootloop ever since.

Have spoken to Apple support who were less than useless, and want £160+ to repair the Watch that they themselves broke which is pretty poor customer service I’d say. Any advice of more extreme methods to fix this would be welcome.

Its an AW3 and Its fully charged.