2008 Santa Fe GLS stereo problem
 

My stereo stopped working altogether and displays "mute phone active" in bright blue on the LCD screen. Also the display never turns off, even when the car is off and the keys are out of the ignition. I dont have nav, just single CD player / radio / xm unit. I tried disconnecting the battery for 15-20 mins to reset everything, but no success, and the screen wont turn off. Also, none of the button are funtional. Any suggestions.

There might be a tiny, pin-hole-sized button on the head unit to do a reset. Look in your owners manual.