Starts and quits

The jeep with start, run for about 3 seconds and then quits. This happened once before and I realized the securety feature was ingaged. Unlocked the doors using fob, problem solved. Now nothing seems to work. Pulled the securety alarm module and the VTSS relay out of the dash, still no differnce. HELP/

What year Cherokee? Is the security system OEM? It seems those security systems cause more problems for the owners than the bad guys.