No audio in car radio

[seabra]

Hi.

I am a newbie in this mater.
I have a car radio (Kenwood KDC-3090RA) and for some time when i put it to loud, i heard some noise on the speakers and it smell like burn circuits but, when it works at low level that never happens. Now when i turn the ignition off the speakers make a sound. Today i take it off and open it to see if i can see anything, when i put it back , it simply don't give a sound. All works (CD, radio) but it has no sound.

I hope someone can help me with some information.