Key Won't Turn, HELP!
 

Our 2005 C230's key suddenly will not turn. I've tried everything I could think of, along with some things I read online; new batteries, disconnected battery, made sure all fuses were not loose, etc.. I have not pulled fuses as I cannot figure out which fuse directly relates to this function. I've even put the key in and out several times to see if it would suddenly start working again, along with cleaning the sensors on the key itself and where it plugs in. Nothing is helping. The door locks work, but it just won't turn. Any ideas on where to go from here? Or, does anyone know what specific fuse to check?

Thanks for any advice you can lend, appreciate it,

EIS module! take it out and send it out for repair. $250 to $500

Dang, that's crazy!! What a stupid key!!!

Ok, well, this is strange, tell me what you make of this. I had the key in the ignition and pressing the door lock and unlock on the key while trying to turn and suddenly it did turn, unlocked the shifter and everything, but would not start!! This battery is less than one year old so I didn't really consider that as a likely possibility. Then I tried to jump start it like I read in another post to tell whether it's the battery or not and it would not start, and the key would not turn again.