We have a 5 year old max-e-therm 200 pool heater. I noticed this week that the heater is displaying two error codes after start up. The heater (when main power first turned on) will cycle through its normal pattern then go blank as normal. About 10-15 sec later it displays AD0 and AD1. The heater will turn on as normal (in both spa and pool modes) and temp adjustments work as well. However I am not able to shut the heater off with the button on the panel. I must use the main switch that controls power to the pool pump as well. Any input would be greatly appreciated.