My battery died and had to get a jump and trunk wouldn't open to get the new battery installed. To open the trunk from the inside there is a release cable located behind the light on the inside of the trunk on the driver side. Pop the light out and pull the release cable and it will open.

 

If you have a trickle charger, connect it to the car at the hood. Make sure the charger is plugged into wall and on.
Then, you will be able to open the trunk without issues. Then make sure to put a cloth of some sort under mechanism, so you do not close it again.