Mamiya 645 winder stuck

I just purchased a Mamiya 645 camera, but when I try to test the shutter the winder went completely stuck, the video can be viewed from this link:, Is it possible I can fix this?

I have several questions:
- Did you read the manual?
- The shutter requires batteries, do you have a fresh battery in the camera?
- What happens if you switch to multi exposure?
- Are you testing it with something to wind on (I use a spool of backing paper saved from a 120 roll for tests, so as not to waste film)

If I remember correctly, it should freely wind (and not cock the shutter) unless there is a roll of film or backing paper, or the multi-exposure lever is toggled.

So maybe the shutter release is simply locked? There is a ring around it to toggle the lock.

PS. If there is no battery and the shutter is cocked, releasing will leave the shutter open. A T mode of sorts that doesn't consume battery power.