I would try running a power wire from the positive terminal on the battery to one pin of the fuse, another wire from the other pin on the fuse and put power to the blower motor fuse terminal in the fuse box. This will provide a fused power supply to the blower motor circuit. This is how you can prove that there is an open in the power supply to the blower motor fuse. Sometimes it is easier to make your own power wire to the circuit at the fuse box than trying to find the broken wire.