Well, now that it
is open, it's a good time to do a little maintenance to keep it operating smoothly- or to get it that way. If you don't figure out all that is wrong with it now, it will fail again- especially in winter conditions, when you may need it most.
Mine used to squeal a little whenever it got stuck- I'd reef on the handle to get it to unlatch. Sometimes only one side would move, sometimes not even one. I got tired of screwing around with the door in the rain while the groceries were getting soaked, so I finally put a light in the door panel to see everything that moves (or should move) when attempting to operate the handle. I hit the moving joints with carb cleaner to remove the built up oil and dirt. Then I hit the joints and pivoting spots with lithium grease spray- don't get this on the window- AMHIK.

You have to use a spray tube to get in the actual latches- keep operating the release handle until the latches move freely in and out with springy tension. Finally get a dab of grease onto each striker in the jamb. Lube these all around.
Get the hinges lubed up while you're at it and the door is now gonna move whisper quiet and latch/unlatch on command. Sounds involved, but it's less than an hour to do.
Pulled the panel off the back and found some loose clips. Made sure everything was hooked up correctly and it seems to be working now.
Thanks!