W211 Issue with Command Radio

[Babyblue]

Hi All,
I wonder if any member or members can help or advise me with an issue with my W211 E class 220 cdi 2008 model.
Just suddenly my radio stopped working and Start would just come on and go off after approx 20 seconds. I checked the fuses in the compartment of the side driver's compartment and in the boot, all seem fine, and no blown ones. Not sure if I need to check in the engine compartment if there are any as someone near me suggested maybe no 26 in the engine needs checking?
Anyway left it for a day then the radio, sat nav, and CD came back into life for 3 days then went off again, and just the star coming on when i switched the command on.
Nothing works sat nav, cd or radio.
Checked all fuses again and nothing has blown! Nothing has been done like changing the battery over or anything like that, and never had an issue with the command before. Can anyone help me to diagnose the issue? Just stumped as to what it could be as its nice to have some music in the cockpit

 

[Babyblue]

FINALLY GOT THE COMMAND UP AND RUNNING AGAIN AFTER THE AUTO ELECTRICIAN SORTED IT OUT. Took about 2 hours to delve into all-electrics like the fibre optic cables etc. The issue was down to the telephone on the command which was set up prior to my ownership wrongly and in the end stopped the command from working correctly.