Hi, sometimes when a disk doesn't mount you can go to applications>utilities>disk utility and look at the left part to see if there's a "connection" with the computer. Sometimes the disk is greyed out and you just have to right click>mount, or to click at the mount point link (blue path at the bottom). If you don't see the disk in disk utility probably there's a problem.
I've had to recover images from my nikon gear, with data rescue, and it did a good job (most of the images were rescued) But I've never tried it with my hasselblad gear... I hope you recover your images, Good luck!