Flu and other auto experts-
Would shifting it into neutral and braking have stopped the engine? Just thinking out loud.

Generally yes. Depends upon how much ‘drive/fly by wire’ the car is. If the same system controls the auto transmission, it may not work if it is ‘confused’. See my earlier comment, method #3. Turning off the engine and then turning back on but not going to ‘start’ (and not touching start/stop button) will cause ECU to restart, possibly clearing problem. If you turn engine off, move autotrans to neutral and then go back to on (but not start or hitting start/stop) it should reset ECU and the engine won’t restart.