Originally Posted by Duster_360

Looks like you were lucky it didn't vent. Obviously, when you 'force' a low voltage lipo to charge, you're supposed to watch for swelling (typically called puffing) and immed stop at any point along the charge (the forced part or the lipo part) if you see if start to swell. Then take it outside somewhere it can't do any damage of it does indeed go ahead and vent/smoke.

From where you are now, it's time to dispose of this one. Harvest the connectors and use a auto 1157 tail light bulb to discharge it to zero volts outside. After 24hr or so, remove the bult, twist the wires together and toss it.

You should be using a lvc (low voltage cutoff) so this can't happen....