help with my Atwood heater please asap

ok guys so ive worked on It for a couple hours now. Replaced the regulator which I didn't mind doing anyways. Smell propane and it fires up then shuts down the same as it was. pulled the whole heating element out and cleaned burner checked orifice and all that. Measured and set electrode close to burner like atwood has told me. Still same result. im at a total loss. what do I do next? I have no clue but to maybe buy a board. im going to call atwood again tomorrow and see what my next step is. Thanks