Sounds like someone yanked a NOT "arc-proof" plug while the unit was charged. An "Old" Speedotron, with melted / fused ... anything. No. I wouldn't use it - not even on a bet!!!
In fact, I'd run like hell is anyone within 5 meters was trying to use it!! There is a LOT of energy stored in those - any - Power Pack.
Someone around there must have a dazed look, and probably, burned fingers.
I love my DynaLites and their arc-proof connectors.