whats wrong?

[pimpinprelude]

I have a kdc-mp225. I got it this year for christmas so its pretty new. well I wanted a lil more bump in the rx, so I hooked the amp and sub up to make sure everything worked before i hard wired it. so everything was cool and sounded good. once the amp and sup were disconected I turned the key on to listen to the radio. At this point it was just the head unit and the 4 speakers. 2 treos in the back and two kenwoods in the front. the power came on and it said it was playing a cd. (i could hear the cd spinning).. but no sound.. i have checked every wire that was even remotely related to the headunit and found nothing. also, i took the radio out and hooked it up to a 12v power source and wired some speakers to it,.. still nothing. did we fry the headunit?? or is it a simple fix? i was thinking the outputs are shot.