On the 46's I've had, there is a counter advance button near the counter window. And with the back open, one of the silver rollers on each side of the film gate is what drives the counter. You can open the back and rotate the roller. Try rotating the roller in the direction it would move with film in. See if it moves the counter and/or releaes the shutter lock.
I don't remember the exact details, but once you get a handle on the order to push the button and the shutter release it should make sense. As I remember, set the counter to 0, load film and wind until 1 is in the window, then slide the button to get the counter to move to 1, then the camera takes care of the rest.