With the trunk lock in the horizontal position the trunk lock will stay locked even when the rest of the car is unlocked.

Vacuum (suction) on the line to the trunk lock should have no effect and will not unlock it. Larry's suggestion would work great if the lock was stuck but in the vertical position.

You might want to lubricate it to prevent sticking in future.

You can order the drivers side lock cylinder from the dealer which will work with your original key OR install a remote keyless entry for added convenience.

Acky