Any signs of 'arcing' on the hood? How secure was your battery and the hold-down clamp? It sounds like you had a direct short on the battery somewhere. This event is bad all over - for the battery and the alternator. A slipping belt "shouldn't" cause a fault like this but it will squeal like a pig if the alternator is suddenly overloaded (see it happen when guys install a big audio system and add a heap of accessories, then try to run the lot with a stock charging system - there is so much load the alternator it prevents it from turning with the belt, thus causing it to slip on the pulleys). Check your positive leads from the battery and the alternator for signs of burn out. Next check your main fusible links for damage or failure. The fault must be on an un-fused circuit or it would've blown something. If you can still get it to start, check your charging voltage with a multimeter. If it's showing anything less than 13.8 volts there's something amiss.