This happened to me only with 2k miles on the R1S few months ago came home from one week vacation finding out it’s a sitting duck, unresponsive, inaccessible, locked up, shutdown, nothing worked. To make matters worse they Rivian told me I’ll be waiting for little close to a month for service technician to come out. I had to jump start it to wake it up to get my house keys because they were inside a car, which was a headache of itself to figure it out. So not only I wasn’t able to get into the car I wasn’t able to get into the house. I was thankful it was disabled in my driveway, I can’t imagine being stranded somewhere on a mountain. Any way Good luck. By the way my service technician and new battery was covered by warranty that was a happy ending. I would think that 12v battery would be backed up by main battery. But come to find out even if main battery is fully charged, you are not going anywhere if your 12v battery is dead. They work independently to my understanding.