2004 SL55 in the USA with only 3800 miles that will not read any CDs in the CD0 slot in the Comand unit. Original owner says the unit worked when he originally bought the car. He says both audio and Nav disks were used and the total time the CD0 unit was used in the last 6 years was less than 1 hour.

I get a no CD is inserted message if I select CD0 when in CD mode. A few times I got a CD reading error message. The CD changer works OK.

If I press the NAV button and put in a new Blaupunkt DX Nav CD, the unit acts like no CD was inserted.

If I enable the Infos screen when in engineering mode while moving, the GPS line and Speed both say 0. How can I test the GPS electronics without a NAV CD? Is the Speed indicator 0 due to no GPS?

Dealer says there are no test CDs that I can buy to test the unit.