did you ever resolve the differences between your procedure and the one on this site that had a few additional steps? did you wind up doing those things too? i had the impression that it had something to do with the alarm, haven't really had time to pore over the details. i am sort of inclined to go crutchfield after an initial read of the instructions.
BTW, i checked with MB parts and the lock is $160 with a new key. that's not actually too bad as a new key on its own is $40 and i was considering getting a new key anyway.