Been there and done that.
I went through this with three different units. All covered under warranty.
I'm afraid that if yours is like mine, it's dead!
To remove the unit, you first have to remove the trim.
There are two slots on the bottom that a flat blade screwdriver will fit into.
Just gently pry the trim off.
Mine had 4 screws that held the unit in place.
Beware, there are 500 Million wires coming off the back of this unit.
(Ok maybe only twenty).
If under warranty then the dealer should handle this for you.
In warranty has expired then I recommend a different unit.
I replaced mine with a "Home Theatre" unit.
(See more about that in Concertone threads)
I can no longer run it on 12V but that is not an issue for us.
Several of the guys here have used the Jensen units and have been very happy with them.
Concertone is pure junk!