water heater works fine - IF- I leave door open

It turned out that it was the igniter/sensor (DSI electrode). Replaced and works as it should. $11. Of course I needless replaced the controller ($90 with cover).

And I stupidly thought while I was tearing things apart, might as well replace the switch ... which wouldn't come out, and wires too short, then wouldn't go back in. Just a tremendous pain for something that should have been easy, and in hindsight shoulda been left alone.