Looks like the battery may have been shorted out so that means a wire may have been pinched and bare wire touched and it arced. Hopefully none of the internals are damaged but as for the battery it's probably toast.
As for the wallcharger, get a "real" charger. Preferably one with a "negative delta V" (means it's a smart charger) rather than your current "dumb charger". It doesn't need to have a fancy LCD screen but at least it should have an LED light that tells you when it's done.
ie. this first one is a smartcharger since it has an led to tell you when it's done (obviously not for airsoft though, that's a cell charger):
This imax B6 is also a smartcharger but 90% of the functions you're probably never going to use: