What do I need to do when rear seat is stuck in the down position

I just had the same problem and resolved it through shear determination as follows: Get a good pair of vice grip pliers and carefully start undressing the seat's backside by slowly popping off the back panel near the bottom. You'll have to get a good portion off, enough to get those pliers in vertically. Look for the thin metallic bar that connects both arms that have the wire coming out, that's your target. Vice grip on that thing so you can turn clockwise. Start at the farthest point so you can get a real good crank. It took me a few tries and I pushed the seat hard by using my wait to loosen it up and when I was about to give up, SOB gave, problem solved! Hope this works for you! Good luck!