If the battery in your Chevy key fob is dead you will not be able to start the engine or unlock the car. On the DIC you may get a warning message stating NO REMOTE DETECTED or NO REMOTE KEY WAS DETECTED. Use this method to manually start your Chevy if the remote batteries are dead.
On the Chevrolet Volt you need to open the storage compartment on the center console. Removing the rubber mat will expose the hole where you can insert the metal key.