Newbie Car audio basic questions ( 2 of them)

[ska]

Hello everyone.
we have an X5 3.0 2002 with:
mk3, Cd changer,Carphone, 16/9 screen and problems...

Easy ones: There is a CD blocked on the cd changer. I can safely open it and remove and everything will work ? or there is a specific procedure like when the same problem arise in the NAV ?

Difficult ones:
There is no sound at all and no radio on the menu anymore.
Phone is working but no sound
TV is working but no sound

the questions : where is located the radio module ? how it looks like ?

I just found a picture of the back ( ?) that show a red fuse but I am unable to locate it or its "inside" something else ?
All the audio is connected to an external AMP or there is an amply inside the radio shared by all the component ?

What do you think that's broken, the AMp or the radio ?

Thanks for your time.