Detachable key blade - detaching/attaching
Removing the key blade
Slide the spring-loaded catch to the side. 
At the same time pull the key blade straight out backwards.
Attaching the key blade
Carefully refit the key blade into its location in the remote control key.
Hold the remote control key with the slot pointed up and lower the key blade into its slot.
Lightly press the key blade. You should hear a "click" when the key blade is locked in.