Just installed-by a licenced friend- a new high effic. Goodman gas furnace- fired up okay for a couple of hours-now it is not- fan comes on- diagnostic panel is blank- breaker is okay, 3 amp fuse is okay, flame sensor reads only 57 volts(should be 120?)- installer figures control panel is fried. Is that most likely? If so going to be chilly till I get a new one.
Thanks

See here