2000 Saturn SW2 Security System

I bought this car a few months ago. Recently the "security" light and "service" light has been on. 3 different times, the car would not start. I tried disconnecting the battery, checking the fuses and it finally started when it wanted to. I took it to the Saturn Dealer about a month or so ago and they put in some new software and something about a faulty passlock sensor and they replaced the ignition housing and cylinder assy. Today, I could not get the car to turn over, the security light keep flashing and will not stop. It has been many hours later and it still is not starting. Do you have any suggestions for me