I replace my battery for my mercedes benz S320 1994 an the radio won't come on
Did you check the fuses?
You will need to go to your local Mercedes dealer or repair center and they can get the code for the radio for you. Check the owners manual in case the previous owner wrote in down in the manual somewhere. This is if you turn it on and it says "CODE" only. Otherwise check your fuses.
Search Mercedes-Benz S-Class Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Mercedes-Benz S-Class Experts