Boot wont open with key fob

Try standing at the rear of the vehicle, putting the fob against your temple and activating it... This realy works!
Replace the battery in the fob.
If all else fails buy a new one from the manufacturers.

The problem which you mentioned is related to release motor,this motor controls the bowden cable via the spring.

Either the motor is stuck up or its near to faulty.

For more detail about how to inspect the motor and replace the motor check the link below:

This will help http://www.allcarhelp.com/2016/05/boot-release-problem.html