Volt advsor recommended shutting down and exiting the car so the fob was no longer in the car. Drove to my destination and called OnStar. Unplugged, got in the car and switched to Hold mode, probably before everything booted up. Why is the volume knob not working on my car? This may be caused by problems in the wiring system or a blown subwoofer.
However, if there is any problem with car amp then you may experience low-quality sound or even no sound from your subwoofers. You should properly adjust car stereo settings for a better sound experience.