In the jammed position are the shutter leaves closed? Ie can you see through the lens (or down the chimney)? If not try that screwdriver/tool thing again, you have to keep going even after you think it finished to lock into the release position.

I had this happen to my 501CM in the past a couple of times. It happened when the shutter button was pressed just a bit so the lens fired but the rest of the body didn't, once it was as the camera was bouncing inside the bag, the other when I had it over my shoulder and the button got caught in my belt as the camera was swinging back/forth while walking.