The watch is only water resistant for 1 meter. I thought it was more, but it also can have its water resistance "damaged" if you drop or impact it in any way. I have done both. My bad.
I never tore it apart until after the pool incident.
And I did notice the back of the watch fogged up after I noticed that it stopped working.
But a quick update, it had stopped giving me the error for a while now. Hopefully it continues to charge normally. It does seem to only last 10 hours now when it used to last around 18 hours.