No sound from my 2008 mercedes s-550 radio - S-Class Mercedes-Benz Cars & Trucks

Probably Fuse 38

It's not the best of charts
https://www.mercedesmedic.com/sl-class-r230-fuse-chart/

Fuses - Mercedes-Benz 2011 SL550 Roadster Operator's ...

https://www.manualslib.com > ... > Operator's manual
Mercedes-Benz 2011 SL550 Roadster Manual Online: Fuses. Introduction The electrical fuses in your vehicle serve to switch off malfunctioning power circuits.

Fuse Box Diagram Mercedes-Benz

https://fuse-box.info > Home > Mercedes-Benz
Fuse box diagram (location and assignment of electrical fuses and relay) for Mercedes-Benz CLS-Class (CLS220, CLS250, CLS350, CLS400, CLS500, CLS63) (W218/X218; ...

https://www.google.com/search?q=2011+Mercedes+SL550.+fuse+garage+door+controller

....

check e/parking brake is off -problem can be a few reasons this forum explains most https://mbworld.org/forums/s-class-w221/221407-first-problem-my-08-s63-any-s550-had.html

The best way to reset it is to have the problem repaired that caused it to come on. Another way is to disconnect the battery negative cable for a few minutes and then reconnect it. This may cause other problems - loss of presets on the radio, and possibly loss of radio functionality if you don't have the appropriate code. And, depending on what caused the light to come on initially, it may just come back on soon after you start driving again.

This video is for another model but I believe it is a good guide to the procedure.
follow the link

https://www.youtube.com/watch?v=D9LiaRugcjQ

They should do but you need to check the offset of the rims.

You will need a mercedes star machine to trouble shoot the radio normally dealer only

Like this...

No that would not be it. Are you using the correct grade of a good quality name brand fuel?

how replace rear speaker

it's a trap, i quess.