The board, if you are looking in from outside, is on the left, it does indeed flash a code, as I recall the code it will flash says "ignition lockout" which really does not tell you anything.
I had that same problem. here is the suspect list and what I found.
IN linear order:
Flame sensor (This is the rod that also generates the sparks)
Many have said if this gets a lot of carbon build up it may not get hot enough fast enough and will not generate the needed voltage to tell the control board "I"M HOT" (480mV or just under 1/2 volt) Mine tested good when I heated it with a volt meter attached.
Connections between flame sensor/spark rod and Control (Mother) board.
The voltage to generate that spark is on the order of 1,000 volts.. if the connections are not perfect that can punch right through, no problems.. As noted above the flame sense voltage is around 1/2. not so good at punching.
NOTE: Two connections (each end of the wire) plus the ground conections.
Control board:
My theory: On my Attwood the same wire carries both the kilovolt Spark and the half volt flame sense.. Well if the change over from SPARK to SENSE does not go well, or happens at the wrong point in the spark cycle (it is an AC voltage) then the flame sensor chip gets hit with up to 1500 volts, This is a chip designed to sense less than 1/2 volt, and we are going to shock it with 1500.. Not likely to survive. And Mine did not.
I ordered a New Dinosaur Boards board from American RV in California (not to be confused with American Rv in Michigan) and when I opened the box the very first thing that impressed me was the construction.l. Very solid, circuit board traces are larger and heavier and well soldered.. All connections looked very good to my trained eye.
Then on to the component side of the board... Well there is a component on the Dino board that is not on the OEM. it is a "Gas Discharge Tube" which is a commonly used device to protect against such things as lightening.. And from it's position, I suspect it is hooked to the flame sensor chip.. In short, it is there to prevent exactly what I think happened to my OEM board.. .And yours.
