I noticed that the heat was staying on much later than programmed. When I looked at the thermostat, although it was 2:30 a.m. which is supposed to be "sleep" time, it said "wake", and the heat was not only still on, but HIGHER than programmed. In fact, getting higher all the time. I don't see any reference to a "reset" button in the owners manual. Other than holding the temperature to a lower number until "wake" time comes back on, what can I do?

It may be toast, but before replacing it I would remove the batteries and kill the power to the furnace (to remove the AC from the thermostat circuit). Leave it that way for maybe 15 minutes just to be safe, then put the batteries back, turn on the furnace power, and re-program it. Maybe that will be enough of a reset to recover it.

Good luck,
WallyH