[Al Skierkiewicz]

OK,
This is not a failure mode we have seen before but I think one of your Jaguars is shorted. So here is a way to troubleshoot the offending circuit.
Connect everything as you would for a functioning robot. PWM wires, power supply wires and motors.
Remove all but one of the circuit breakers and try driving. If all is ok, then pull the first one out and put in another one. This test will show if one of the circuits is shorting the power supply. Then you will only have to check in one circuit. This should show that one of the four controllers is causing the problem. Check all your wiring in that branch. It is possible for a small strand to short across two terminals and cause this problem, so be sure of all connections. Take them apart and inspect each in a bright light. If you need to call I will be home for about an hour. I will PM you with my home phone.