Hi Laurent, l'm using 2000 FCW model and maybe there are some minimal operational difference between this two models. Do you have fresh battery in the camera? Did you try to operate camera with out the lens? What kind of lenses for your have on the camera? C, CF or F? Do you have manual for the camera?
I just tried my camera and with out battery it behaves in similar way that you described.
Did you try shutter setting "C" (for using C lenses with this camera) in that case camera body shutter works just as secondary (as in 500cm), the main shutter is in the lens. 3 setting in the middle of advance crank are just for different modes of mirror operation.
Good luck! Please let me know if you need operational manual.