Spent the last 4 months going back and forth with apple on this issue. Watch was perfect when I got it and after an update it would die in 12 hours or less with normal use (as outlined by Apple). They have refused to do anything other than "collect data" which they cant get the software to work to collect the software. One advisor approved a replacement and sent me to a store and when i got to the store (and sat for an hour waiting) I was told they dont do replacements at the store. Finally gave up today and told them I am not spending any more time on this and will just get rid of it and not get another apple watch again.
really sad to see apple not taking care of customers and obviously there is an issue with their devices given the amount of folks on here with the same issue.
I tried the resetting and repairing but didnt do anything. Deleted 3rd part apps etc. etc etc. nothing worked.