How can I fix my 55 plate Vauxhall Combo stereo?

I have a Vauxhall Combo van with a tape deck in it. I tried to put a Vauxhall CD player in the van but are getting no life out of it, when I put the tape deck back it I can not get any life out of that either. I have checked the fuses relating to the infotainment system and the fuse on the back or both stereos, they are all OK. What else could cause this problem?

Steven Camilleri
June 2011