Air bag light on

If you unplugged the initiator wire going to an air bag, then turned on the ignition switch, the computer would detect that, set a diagnostic fault code, turn the warning light on to tell you, and turn the system off. There is no other defect so all that should be needed is a scanner to erase the code. Most aftermarket scanners will do that now so you don't have to go to the dealer.

Check with some other shops. Aftermarket scanners are always a few years behind the manufacturer's stuff, because they don't give up that information. The scanner manufacturers have to reverse-engineer many of the computers to figure out how to access the information. If no one can access your car, it could be because of its relatively low production volume and limited demand. Those take a few more years before they catch up to the more popular models. In that case you're stuck with the dealer.