Removed the control panel to test the switch on the latch and the thermal cutoff with a meter (both working fine). No sign of water or corrosion in the circuit board, so all that was left was a failed control panel. The online pro at AppliancePartsPros identified the right part for me, found a picture for me to compare with the busted one. New part was cheaper than a number of other websites, and arrived in 24 hours (though I only paid for standard shipping). Swapped in the new control panel, and ten minutes later, had a working dishwasher again. Thanks Folks!