I thought I might be having a HV voltage leak but later found that it was more of a capacitance effect. I could read a voltage between the frame and the battery pack but would quickly fall to 0 within a few seconds. This still may be somewhat contributing.If I remember correctly you are also experiencing brief “voltage leak” phenomena in which your voltmeter test was reading voltage briefly on the chassis ground?
I can’t recall but did you at least isolate the source to be from pack 2 ? Maybe both are related ? Essentially what I’m getting to is there might be an arch of some kind from pack 2 that is causing this leak and or boot issue?