I believe I had the same issue. I could not get my hot water tank to heat on propane. I simply turned it off...made sure my propane tank was turned on, then hit the switch. The dogon thing fired right up.
I was told that if your unit is not level it wont work. I was also told that if you hit the circuit breaker switch and leave off for a couple of minutes...then click it back on it will reset itself also.