My furnace is turned off. I came home and main blower fan was running, t-stat is in the off position and fan switch is in auto. Batteries in t-stat are changed. I turned power off to furnace for five minutes and turned back on, then ten minutes later fan turned on again. Any suggestions would be appreciated

Every time I've seen this happen with this model furnace, the problem has been in the circuit board.

Is there a fan relay that maybe stuck?

Its part of the circuit board