Carbuff, I'm in the same boat as you. I got the yellow wrench "see manual" message while driving in that snowstorm a couple weeks ago. I made it home, but the next time I tried to start it the SSN message appeared along with the yellow wrench. When plugged in the EVSE lit up like it's charging but the car didn't actually charge. I put a 10-amp charger on the 12v battery and let it charge for a few hours but the next day it still showed the SSN and yellow wrench. I had to go out of town for a week the next day and didn't call roadside assistance until I got back. It was still showing the same errors and still refused to charge after sitting for a week.
The dealer said they found something like 25 dtc's, including one indicating that the HVB connector has a "massive open short". (He said that a few times, I have no idea if he knew whether he meant a short circuit or an open circuit.) They ordered the replacement wiring harness which they should be ready to install in the next couple of days. He says they'll have to wait until after it's installed to see if that's the only problem or if there's also something else wrong that tripped some of the dtc's.