Due to breaking the tiny pin that holds the blade into the fob and the fob keep falling off I purchased a replacement case to transfer the guts of the fob into but after having issues getting the new case to fit together with the guts inside it now doesn't work. None of the 5 buttons do anything but once inside the car will not recognize the smart key until it is inserted into the cubby box slot then the car will start.
The other key will unlock the car but also will not start it unless plugged in but that one never has so is it possible to teach the dumb key how to be a smart key again or am I screwed into paying out for a stealer to do it.
Would really appreciate some feedback or magic cure.
Pete.

Hi Peter, I believe there is a time out element to the smart key where if it does not have power from the fob battery for a certain period it loses it's programme and that may well have happened to you during the swap over.

I believe the programming of the keys for the Modern XK (X150) has to be undertaken by a dealer and of course you need to provide proof positive that you are the owner of the vehicle for which you are trying to reprogram the keys.

N6 JMX