Mercedes S500 2003, jumped battery radio does not work?

You will need to get the radio code. Look in your owners manuel. If you can't find it there contact your local friendly Mercedes- Benz dealer. Have the VIN handy. Your radio thinks it's being stolen, that's why it's not working.

As long as your battery have enough power, try and disconnect your battery cables and leave them disconnected for 10 - 15 minutes and then reconnect your battery cables. Start your car and see if your radio volume comes back? Hope it does,but--- You may get some other fault codes like Presafe inactive, etc. Do not panic. Just take your car for 0.5 - 1 mile ride, get back and cut your engine off. Wait for few seconds and restart it. Hopefully your Radio should work and all fault codes should go away. If the fault warnings do not go away, use the "R" button at the right hand lower corner of your instrument panel and hold it for three seconds or so. A message will pop up asking you, if you want to set your car back to factory settings? Select yes. It will say settings are reset to factory setting. Again hopefully all faults should go away. In case if your radio volume is still not working, it may be that the radio fuse got blown you jump started. Replace the blown fuse. The radio fuse is in the fuse box behind the rectangular panel, located below the front vertical face, below the rear passenger seat. Good luck.

maybe theres a loose connection to the radio. or bad ground wire loose.

No it's the fuse at the back. mine didn't work for months and when auto electrician checked it was the radio fuse and I have had the same on my wife's 2007 c class too