Replace this part as it could cost you thousands of $$$$$$$$$$$$$.
Emergency rear cargo access kit.
In the Discovery 3 and 4 the rear cargo upper tailgate is released by an electric solenoid connected to the door catch by a cable. As the electric solenoid pulls it releases the catch and the upper tailgate can be opened.
This cable has a cast elbow on one end and it SNAPS at the 90 degree bend making it impossible to open the door by pushing the release button.
To repair this once it has failed is quite hard and it is necessary to be quite forceful to release the inner trims, but it can be done if you know how. It takes about 1.5 - 2 hrs to replace the broken catch / cable assembly.
WARNING
If you like touring and have draws, cargo barrier or any other accessory that will limit access to the rear cargo space from the passenger doors it will be impossible to open the rear door.
If the cable does fail, and access to the cargo area is not possible the only way to open the rear door is to cut a hole through the rear lower tailgate causing a costly panel shop repair, which will cost thousands.
GOOD NEWS
The good news is Land Rover have finally fixed the problem and have released an updated part with a solid steel elbow rather than a cast elbow. This should fix the problem from happening in the future. The part number of the up-rated part is LR017470
It is recommended to replace this catch before it fails as this repair is cheaper.
EMERGENCY ACCESS KIT
Les Richmond Automotive is also working on a manual release system as an emergency access override.