Ordered a replacement master key (blade only, no remote included) for a '97 e420 from my MB dealer. The key opens the door okay but when I tried to start the car with this replacement key, the engine cranks and tries to start but stalls immediately. Then the green and red rearview mirror lock/unlock lights starts blinking.

I spoke to the MB dealer and was told it is the correct key and maybe I have to insert the new key several times in the ignition switch as the tumblers might have taken a set on the original key. I thought this was absurd but I tried it anyhow... it didn't work. I also asked if it was magnetically coded and if there is anything special about it and they said no.

Any ideas what could be the problem? Appreciate any help before I lose or break the only key I have left. Thanks!