I could be wrong but I do not believe my thermostat has and buttons or levers other than the temp control selector lever/switch on the top that goes from left to right. Moving it to the right usually turns on the furnace and heats the RV. Moving it the left usually turns the blower off and thus the furnace as well. It is an old school thermostat. It is not digital.
I agree with what you guys are saying. I think it has to be something simple as well. It seems weird that it would all of a sudden not stop blowing. The only thing I did different this time was to disconnect the coach battery for three weeks. That blower started the second I connected the battery and stayed on until I disconnected the battery every time. I know because the vent for it is close to my battery compartment outside. As soon as I connected the battery, I was hit in the face by air venting from the blower motor.
I also switched all of the fuses off and it kept running. I did not take any of the fuses out though.