Radio stops after 15 sec following upgrade from 1 to 6 disc player

[heinheinsen]

Hi

I have just installed a used 6 cd changer in my V70 2009. Prior I had just 1 disc. 
Now I am experiencing a few problems:

1) The radio (FM) switches off after approx. 15 seconds.
2) AUX also switches off after approx. 15 seconds
3) I cannot access the CD player

Anyone have an idea how I can solve that problem? I replaced the radio unit without disconnecting the wires in the console.

Thanks