So, 5 weeks at the shop now. Keeping in mind that I'm not all that up on ev terminology or technology, my understanding of what they've told me so far is this.
They took the big battery out to explore stuff inside it. I'm told they were more likely to just replace the whole battery in the past, but they investigate more now. Their first guess was the PRA (Power Relay Assembly), but replacing it didn't fix things. Then they found a "blown major fuse" inside the battery which the Hyundai techs believe was caused by the "battery heater". So they are ordering a fuse and heater and I should hear this week.
Likely due to my lack of knowledge, I'm a bit confused about the "battery heater". I'm in Canada, so I've got a heat pump but I don't think that's what they are referring to. And I have an option to turn on battery preconditioning, but have never done so. So I guess there's some other form of "battery heater"?
To be continued ....