Several members' boot lid have stuck.. this article describes an approach that may help you. This is not a step by step set of instructions, just more info.

Please be aware that some damage will result to the trim, but these items are easily replaced.

I suggest that this article is read together with Lofty's article

As the problem affected our earlier car, with the button rather than the handle type opening, a slightly different approach was adopted.

Remove the main panel trim from the door panel, it is help in place by several plasic clips

Cut the trim near the lock on the door, its quick thin at this point. It can be carefully cut, bent out of the way and reglued afterwards. Picture shows moulding removed from car. You will be cutting from the inside of this.

An allen key can be used to release the lock, or it can be forced open with a screw driver. The picture below shows the direction that the lock opens in.

In this case the lock was jammed due to the anti-rattle coating coming adrift. The damaged bit was removed with a Stanley® knife.

The lock was re-assembled without the button to check that the boot could be opened from the outside