I am having same issue. Apples lame fix suggestions didn’t work. I turned everything off set watch to minimal power and still drains from 100% to 0 in less then 2 hours. I even went so far as to completely reset / delete everything on watch and then reactivate it. Only minimal charge ding that ie.. add about 10 min before it drained to 0. Used to last around 30 hours prior to update. Why is the consumer being forced to be the “test bed” for updates?
Years ago 24 + while serving in the military, where I was in charge of the wide area network for a large Base I wouldn’t even think of pushing out a router, switch, or hub IOS update without putting it on a test bed for a minimum of 30 days running as close to every system I could over it before doing the update, to ensure little if any issues.
Seems like the easy fix is to push out a revert back update so the customers could still have use of there watch, along with an apology, while fixing and testing the new update to ensure it works correctly then issuing it back out.
But maybe I’m being too logical.
Maybe what should happen is the laws need to be changed making the manufacture responsible for any damage the update may have caused to the device, and force them to fix/replace it at there expense, along with compensation for time lost not being able to use said device. Similar to what the EU did with standardizing the cable interface for all devices, which forced Apple to put USB C on all there new devices and finally getting rid of the horrible lightning connector.