Help!! Won't Crank
Before I go on - Are you sure you have the right connections on the battery - Check the Polarity - POS and NEG - the battery you received may be different in configuration.
Poles are different in appearance. Double Check Please.
If Backwards you may have easily fried some wires. See below;
Sounds like you might have a short - look for any fried wires. Check your wiring Before doing anything else. Any bad wiring or mice problems. Check it all very carefully.
Hope this helps,
Bcudamatt