There are no batteries in the Pro version, nor are there any double exposure prevention interlocks.
But there are protections built in to prevent releasing the shutter if:
1) the shutter cocking lever hasn't been fully advanced;
2) the dark slide is fully inserted;
3) the revolving adapter isn't turned completely to either the landscape or portrait orientation; or
4) the revolving adapter isn't properly seated fully and locked.
I would check all of the above, focusing particularly on the sliding locks for the rotating adapter.