Originally Posted by Yak

First a nit to pick: probably a question for the audio/multimedia forum, not diesel.

Now to be helpful - the radio lights are off a separate power wire and fuse. You can actually unplug the radio from its prime power via the cigarette lighter and the lights will still work.

Check fuse 4. Read this post.

Keeps blowing fuse. A little help? - PeachParts Mercedes ShopForum

Maybe check/inspect the ashtray connections. The ashtray itself is part of the electrical circuit. If it's not pulled out all the way and has good clean spring/pressure electrical connections then the lighter will not work. But IF the radio used to work untill recently AND was the factory install, THEN you do have power to the circuit.

You can also check the fuse on the back of the radio. PM back, or search for some posts by me with "radio" if you can't see how to remove the spring clips retaining the OE radio.