Hey all, I need some ideas here. I had a series of events that have basically left my 2023 Taycan Turbo S unable to start again due to 12V issues.

1. I was leaving town and had the car in my garage at 100% charge. I had been driving it basically every day or every other day. I was gone for a little over a three week work trip.
2. A couple days in, my wife borrowed my charger since our daughter was using hers )and did not put it back). The car was still at 100% HV charge but was no longer plugged in.
3. During this time it was very cold, around 0–20°F.
4. I got home after three weeks and waited for the snow to melt(4-5 days). I needed to swap it with another car I had in storage that was due for service. When I went to move the Taycan, it would not start or do anything.
5. I read up on how to use an instant jump starter to at least get the frunk open. That worked. After a couple tries, I was able to use the same jump device to get the car to power up. The HV battery showed 98%, but I got a low 12V battery warning.
6. I drove it around for about an hour thinking, like a gas car, that driving it would recharge the 12V battery. (This is my first BEV, clearly.)
7. I drove it to my storage place, swapped cars, and plugged in the 110V Porsche HV charger I keep there. It only worked briefly before giving a charge error (ti always does this on this charger fwiw). I left it anyway as I had to get the other car to the dealer.
8. Three days later I came back to switch cars again and it was dead again. I tried the same jump trick, but this time I could only get the systems to power up briefly before the jump starter pack threw an error and the car died again. I could not fully get the HV system to come online.
9. I have tried several things since:
   * A plug in charger that says it supports LiPo batteries, but it just gives an error (it did this at home when this first started too before I got it to work the first time).
   * The Porsche charger that came with the car I tried at storage, which complains about not being grounded.
   * My old BMW 110V charger, which gives a fault.
   * Even my large Anker portable power station to power the Porsche charger, but that also gave a grounding error.
10. My last attempt was buying a CTEK 4.3 charger after reading about it on the forums. Even that was frustrating. It never even attempts to charge. It just blinks the green light as if it does not see a battery at all. I really thought that would get me out of this mess.  When I run in test mode it just says the battery is extremely low.

So that is where I am. I am honestly shocked that the 12V battery could be completely shot. I have never had an issue before, and I cannot believe this happened after just three weeks of not driving it, although I realize keeping the HV charger plugged in might have prevented it.

Help me please. Otherwise I am looking at towing this thing two hours. Thanks.

12v Battery Issue Help!