For checking out what's going on with the batteries, check out:
https://github.com/martinbogo/i2-battery-diagnostics
https://github.com/martinbogo/i2-bat...stics/issues/5
At this point, risk of corrosion for the BMS in older LifePo4 batteries is very real. For the even older NiMH batteries, I would be amazed if there is no damage.
Do you have a set of known good batteries or any thing else?