There’s some good advice above, but if the crank mechanism is rusted solid, you can attack the toggle piece on the end of the cable. It’s accessible from below as it slips through the hub center. If you can get it to slide far enough to the side and tilt it up through the hub center. You will wear the tire as it falls free.
If I remember correctly, you can block up a jack and use it to pop the secondary latch from underneath if it's frozen up as well. I know that system has caused a bit of angst in more than one person.
