HELP! V8 1998 WIRING FAULT!!!!!

[steve buckley]

couldn't start car then smoke came from under the dash!!! found the burnt wire but can't trace where it goes. there are two blocks and main battery lead which come up from the rear to just in front of the handbrake the problem wire has burnt from the white block up under the dash. the block has 15 wires coming out and it is number20 on the block a black one that has gone. can anyone help with why or what has gone wrong.thanks