Removed LeSabre's Dash Now Won't Start

Yesterday I removed the dash from my '95 LeSabre to install a new aftermarket radio. I tried to start the car once I had the headunit wired in without the dash attached, but it wouldnt start. I assumed it was just an antitheft feature so I finished installing the radio. I put the dash back on and tried starting it again. It wouldn't start with the dash on either. When I try to start The motor will turn on and start to run but then sputter and die. I'm still wondering if it is some kind of antitheft device I accidently tripped. I lost one of the dash screws that goes into the A/C vent hole, would that affect anything? Please offer any advice or help you can!