Water Heater Wont Stay Lit

Here's the Service Manual for it courtesy of Chris Bryant. I believe that in a way above my paygrade, the Ignitor serves as a Flame Prover. Not the old Thermocouple way, some kind of ionization test. So I'd guess that if you broke it you need a new one.
Did you get the Control Board wet?
I do know that Atwood water heaters are bad about poor contact at the edge connector to the control board. Unplug, clean the board edge contacts with a pencil eraser, re-tension the spring contacts in the connector with a dental pick.