I've not seen many cases on here where there was a solid short like you are reporting. Non-approved coolant (Dex-Cool concentrate and deionized water) could potentially cause that error. No isolation would be a serious safety risk.
Given that the high-voltage battery appears to have about 10 years of life in it and there are no new cells available to repair them, you may need to decide if it might be time to let this one go based on the news you get.
Given that the high-voltage battery appears to have about 10 years of life in it and there are no new cells available to repair them, you may need to decide if it might be time to let this one go based on the news you get.