OK, so the car apparently had had enough time to think about what it had done and now it is working normally. It was sitting there, no outside door handles, no headlights, no 12V at all. I put the key in, turned it, nothing. Turned the key back, car turns on. I dismissed the errors and warnings, took it out of Tow Mode, tried to put it into gear, it insisted I wasn't pressing the brake pedal (I was, and the brake lights were on). So I tried to charge it, and that worked. After the charge, the car behaved normally again. So, yeah, scratching my head here. I'd really like to know what was going on so I can arrange to have it not happen again.