The buttons don't need power, they're just switches. That's why they work and the motion does not. There is circuitry in the mouse that needs power.
If you've got the rev 6 motherboard, it sounds like the fuse is blown. Not exactly a Radio Shack part, but you should be able to get one from a real electronics distributor. I think we got them from Mouser, but that's over here in the US. I don't know the EU dealers.
good luck