Can try going in from the front seat area with a long thin bar and try to wedge it into the lock mechanism to force it open. Or if you don't mind "modding" it a little you can drill a 1/2" or bigger hole in the bottom of the undertail so you can reach in there with a screwdriver and release it. Then just plug the hole with a 1/2" rubber plug. Or remove the clips that hold the tail fairing to the undertail and carefully try to flex it back far enough to get in there with a screw driver, but you run the risk of cracking the tail then. Theres ways to get to it, just keep trying till you manage it.