If you have a 12V replace battery warning, that warning doesn't clear unless you disconnect under the rear passenger seat, wait a few min and reconnect. As best I can tell, the car remembers all the faults unless it loses power from the penthouse 12V connector. It's as close to a "fresh start" as you can get. In fact, when Ohmmu batteries were throwing false 12V errors, the workaround to do updates and temporarily clear the error was to disconnect the negative terminal, then disconnect the penthouse connector, wait a few min, and then reconnect.
The 12V battery is really just life support for the car when it's "asleep", and a way for the car to regulate power demand on the 12V system.
Upon exiting the car, the car will eventually go into a deep sleep mode. When you power off, it's basically the same... tapping the brake will "wake" the car again, so clearly the 12V is still on-tap. In fact, unless you disconnect the rear seat connector, as far as I can tell, an "Off" car still knows to top off the 12V battery so often.