Scirocco Central

I have changed the battery in my 2009 scirocco 2.0 gt and the radio/sat nav has not powered back on. I have checked all the fuses in the engine and in the dash and they are all working. I have had the head unit out and the power wires have no power running through them. Any suggestions?

Thanks

Is the battery fully charged? I remember reading that with low battery the car automatically shuts down non essential electronics. Didn't say exactly what but maybe! Just throwing ideas out there