I would assume a charge port failing to open and close isn't related to the 12V battery but maybe it does power that? With the settings all being reset, I thought maybe software related or maybe I held down the scroll wheels and brake for too long and that factory resets everything? But now you have me worried we will be on the road in the middle of nowhere and the 12V will die and we will be stranded with no cell service. Maybe I can stop in the SC in Denver when we are there and see if they can check it quick to feel a little better for the 2nd half of the trip....fingers crossed. From what Im reading, only Tesla sells that specific battery in the model 3 so you cant just use any 12v from autozone?
The chargeport door actuator runs off the 12V system, so it's certainly possible that the symptoms you're experiencing are related to a 12V battery fault. With the number of issues the vehicle is currently experiencing, I would strongly recommend not going on a long road trip until you can at least have Tesla run remote diagnostics/push the firmware update again. If you're still intent on taking the Model 3, then keep food, water, blankets, etc. in case you don't make it to the Denver service center.