My charging issue turned out to be magnet interference.
I started having problems as reported above about a week after I got my watch (i.e., even with watch apparently properly seated on the charger, it would heat up but not charge). After having mixed success with various reset combinations, I realized that the problem had not started until I switched from the classic leather to a Milanese Loop band. I had a hard time keeping the steel and magnets separated from each other while charging and it appears that the magnet on the band or the band itself was interfering with function of the charger I started detaching one end of the band and stretching it out flat while charging and I've not had a single problem since (3 weeks now).
I have also tried an after-market charging stand (Spigen) that holds the business end of the charger off the table, letting the loop of the band hang below. This has also worked well, and allows charging without detaching either end of the band.