The battery is fine, problem is the isolation contactors in the HV electricity distribution junction box. Contactors overheat, most likely melting their electromagnet windings. No more electromagnet pulling the contactor closed, springs push it open, isolating the battery as designed for a fail safe condition, no more power. Though the fail conditions are supposed to be “control system is not happy, cuts pilot voltage to contactors”. Instead of the contactor itself being the failing part.

But hey still, atleast it’s not welding the contactor closed, that would be way worse.