Broken 650 seat cable "cannot get open" fix
I have just had this problem and now I will submit the fix I came across. I read about one guy struggling even with a crow bar to get the seat up. After studying the latch design via picture online, I realized that if I could get close, I could pop the lever, which is just what I did. The lower Tupperware over the license plate is held on my 4 plastic pins. Then the upper Tupperware is held on by two plastic pins in the rear by the tail lights and two on top just under the seat edge. they can be pried up and out. With that the upper Tupperware can be lifted enough out of the way to see the latch. On the back side is a slot in the frame to the back of the latch. If you shine a light in there, you can see the bottom of the latch and the lever. A screw driver can easily go in and slide the latch to the right and "pop" goes the latch and the seat is up. Did it quite quickly actually. My problem is I had gotten water in the cable and it rusted in two. I took the left over cable and looped it and crimped on a cable swedge to create a loop for emergency purposes until I get a cable replacement and have the time to actually install it.
I will try and upload pictures later.