I have the combo unit. Mine would not go into the start a cycle. Travel to the next site and it would work. After several times it would not function anymore. We had several brown outs at one RV park with very low voltage. We do have a Progressive surge protector internally installed, but at one volt above the cutoff voltage was too much apparently. For the living room TV and convection oven as well. I suspect this is what caused allthe problems. I called Splendide and was told the control board was bad. I had purchased the extended warranty and they sent me a new control board, the installation instructions which was the technical service manual, and color pictures for the change out. I wanted to do the work myself. They would have paid a RV dealer to do it. I know the dealer and would never let them touch my fifth wheel. So you may need a new control board and it is not hard to replace.
By the way, the control knob on ours does not spin when running. What model do you have? We have the knob that sets the type of running cycle and the knob the set the time for the drying cycle.