i was having a starting problem with failure to go to READY even with jump-starting from a good running car at 14 V.
A weak, old or worn out 12-volt battery can cause issues during charging. There are a multitude of relays and contactors which must be properly sequenced for charging the pack. If the 12V lets go for some reason, then relay contacts can be welded, or arc and frost the contact faces such that they no longer function properly.
There are high currents flowing in the boost transformers of the OBC, and if the current path suddenly goes open circuit, then a high voltage discharge will occur that can damage the diodes and IGBTs of the boost stage located in the epoxy-coated plate bolted to the liquid-cooled heatsink.
i don't know if the FSM has procedures to troubleshoot the main contactors and relays, but worth checking into this.
Good Luck and keep us posted on your findings.