GMC Troubleshooting Questions? Ask a Mechanic for Answers
If the key is worn, it is possible that it will not turn the ignition lock or the door lock cylinder. In that case, the best course of action would be to have the dealer cut a replacement key from the VIN. They typically charge about $35 to do this. You do need the key with the transponder chip to start the vehicle, otherwise the antitheft system will prevent starting.
If there is no security light on or flashing, then the key does not have the transponder. Next step is to check for spark while cranking. If you have spark, try starting fluid. If the engine fires off with starting fluid then you have a fuel problem, likely a bad fuel pump.