I have the exact same problem. I charged it to a 100% twice, discharged to 0% within 4 hours. Factory reset it twice. Deleted and installed the app twice. I even reached out to the clock face developer without any success.
So looks like function has returned to normal. I did a couple factory resets. Eventually I just left it in a drawer for a couple days until it was completely dead. Maybe dried the sweat or water from swimming out?
I will monitor for the next few weeks.
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