Mercedes W203 command pre-facelift

[Mercedes cozy]

All

I need some help if someone can point me in the right direction.

The command will not switch on. I have found that the NAVI fuse number 64 is blown and when I replace the fuse with a new one it blows again.

What others things could I check?
There is a CD changer in the glove box as well.

 

[Stratman]

Does the fuse blow as soon as it's replaced or only when you attempt to switch on the COMAND?

 

[Mercedes cozy]

Does the fuse blow as soon as it's replaced or only when you attempt to switch on the COMAND?

The fuse has blown after I put the ignition on or pressed the on button, I need to double check.