Have you thought about how this mechanism works?
Normally, as you pull the rewind shaft up, its shoulder pulls up the tab that is formed by the top end of part 708 in the repair manual diagram on the previous page. That tab is just visible if you look down into the hole. It's just above where the film cassette would be. Because the rewind shaft is fallen in, your goal is to pull that thingy up with an improvised hook, just like pulling the knob up would do ordinarily, and the back will open.
You don't need any screwdrivers, you don't push down towards the base of the camera, you don't take off the base plate. I don't think I can explain this any further and maybe you need to show the camera in-person to someone who understands film cameras.