Spray some lock lubricant (Lock-Ez) into the switch and work the key a bit in as many directions as you can. In a pinch, WD-40 will work, but it dries the lock out, so use a good graphite lube as soon as possible afterwards. Push down on the trunk lid as you try to turn the lock. Anything in the trunk that pushes up against the lid will hinder opening. A dry, sticky latch will, too. If you get the trunk open, lightly lubricate the latch mechanism and sparingly lube the latch post with the recommended BRP lube, waterproof grease, or silicone grease. Also lube the cable with a cable lube tool. If the lock still won't turn, take off the panel where you change the oil, and reach in until you find the latch cable. Pulling on it should release the latch. Then see your dealer to deal with the ignition switch or bad cable.
Ypu may want to consider adding an emergency release.
http://www.spyderlovers.com/forums/showthread.php?6760-Emergency-Trunk-Release