RepairPal Certified shops can diagnose and repair your 1996 Cadillac Seville. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
If it is the key fob, then it is likely to be the control module or whatever interacts with the remote inside the vehicle. There is likely something to be wrong there, and you'll likely need professional help with resolving that.