Well, I just got back home, parked in the driveway and pressed the button to power off. Then I noticed the nav was still all lit up. The dash was completely dark except for the security light that always blinks when the car is off. But the nav was still all lit up. So I pressed the power button a couple more times and then it shut off completely.
Is there a scenario in normal operation where the dash would be off but the nav would be on? Has this ever happened to you?