1998 Nissan Sentra Imobilizer, car won't start

We just purchased a 1998 Nissan Sentra that ran perfectly, no problems. It has an after market anti-theft device that has a little plastic disk that you scan, it beeps twice, and then the car will start. After two days, after starting fine, the car died and now will not start. My husband disconnected the anti-theft device wires and reconnected it to how it was
originally. The car is getting gas and spark, but still will not start. Could it have something to do with this anti-theft thing? The brand on it says TSS, but I can't find any information on it other than the 1-800 number on the disk, which is now a gay porn number. My husband says that if it is getting spark, it must be disconnected. Any suggestions? Thanks for any help. We are getting a code reader today to see if that will tell us anything. Any help you can give would be great.