you probably shorted something with a little too much solder. Don't know what you fried, but you probably just blew a trace somewhere. You're not going to find it. I have an xbox with a fried systemboard (not my doing!), I haven't been able to find commercially available replacement boards, but I haven't checked ebay yet.

1999 Silver Frost SVT #609 of 2760 Quaife, lightened SVT Flywheel, SPEC stage II clutch, removed resonator, k&n drop in - various other goodies too.