The fact that you could get the heaters to turn off might be a good sign. Before you go too far I'd double check, fill it up with cool water, set the temps again and see what happens. Checking the circuit board for moisture/contamination if you can. I've spend a lot of my life working with electronics and one of the first rules is to see if you can replete the trouble. Of course the first rule is: If the magic blue smoke escapes you are in deep trouble!