I have a friend that had a FireStorm 18v. After his 3rd charger stopped working he just gave the drill away. Ridiculous how shotty their battery chargers are (or used to be anyway).
Is it one of the older Firestorms? The kind with the 2 prong connetion? You realize don't you, those old Firestorm batteries are interchangable with DeWalt batteries. I would assume that means similar DeWalt charger units should also charge those type Firestorm batteries. I mention this just in case you have any DeWalt hardware that you could use. Buying DeWalt stuff will be even more expensive so that's probably not an option. Although, a DeWalt charger is surely not going to fail like those B&D disposable chargers.