Mike thats a nasty result mate hope you dont have that happen again
BTW what charger were you using
one of my first packs was a set of second hand GP3300 peak matched packs I bought a second hand GMVIS Charger and charged it walked away dont know how long for but it must ofe been atleast 40 mins came back to a molten pack even the bars unsoldered because the shit charger didnt Delta Peak