Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi, my name is***** first step in diagnosing a key that will not turn is to first make sure that the car battery is fully charged and then try a second key. If you don't have a second key you will need to order one from the Mercedes dealer. If neither key will turn in the ignition you will need to replace either the electronic ignition switch or the electronic steering lock. Further diagnosis is done with the Mercedes Star Diagnosis tester.
Let me know if you have any questions.