S4 satnav retro fit

[m444nts]

Hi all i'm new to this so go easy on me.

I recently purchased a genuine satnav plus for my audi S4 cab. while trying to put the code in it just kept going into safe mode. place where I got it from says I need the "safe wire" changing so it has a permenant live. also the head unit is also not coming on and off with the key you have to turn it on and off on the satnav.

can anyone help 

cheers

ant