My key stopped working the other night. The second I pulled it from the ignition, it seemed different, like the shifter wasn't in park but yet the key still slipped out? (Checked the shifter to make sure it was in place and the same with the steering wheel) Directly tried to turn the car over only to find the key wouldn't budge. Tried to lock the car and got nothing. Replace the batteries and nothing still works. I have noticed that the light on the key fob only blinks when i press lock and not unlock or trunk. Checked fuses for moisture in engine and trunk.

 

could be a bad key, its always good to have a back up key. especially when driving a benz. make sure the car battery is good before you do anything.