Car was towed to dealer. Dealer did the following (from the invoice -- paraphrased).

Performed short test. Found no codes. Removed battery to get to locking control module. Test for power and ground and tried test module. Made no difference. Removed side panel in trunk to see if wet. No signs of water. Bypassed aftermarket alarm system and didn't make any difference. Replaced K 40 relay and car started. Performed short test and cleared codes from unplugging control modules and test drove auto.

Total cost was just over $500.

The K 40 relay cost just over $100.

Service manager said the K 40 relay was shorted, and that they had also cleaned some contacts in the wiring harness.