Short Curcit? My buddies got an MTX TC2002 and try'd hooking it up, the amp is on but the sub cuts out, could that be power from the amp cutting out? the sub works with another amp. if its the amp what should do to fix it?

Call up MTX at 1-800-CALLMTX and one of the customer service guys will help you out, even if the amp's out of warranty they still support the product over the phone for as long as you've got it.

The amp have an input harness? those can go bad, or maybe line level inputs are loose. If its not just a loose connection on one of the amps inputs (speaker, line, or power) leading to the circuit board( which could easily be soldered back to the corcuit board), than your looking at an integrated circuit problem- not easy to fix.