When you say it doesn't work....
Are you saying just the 12v
side of the operation or, in all modes of operation?
(the old on was burned out at the 12V heater element connection)
Did you find out what caused this to burn out and, repair it first before replacing the old board with the new one?
Did you check or replace the electric heater element>??
If the old board got this "stressed" to burn out, I'd double everything all the way back to the circuit breaker to be sure you're good to go~Another thing, even tho you've replaced the old board with a new one..there's a remote possibility that, if the 'original problem' was still there that caused the old board to fry...it may very well have zapped something on the new board..check for fuses, etc..
I'm sure you find the problem in time..