For those with a different motherboard than in the answer above: I HAVE THE SOLUTION.
You may have noticed that there are no write-protect pads on your motherboard, as circled in the image above. But look closer! There are two ''tiny'' little solder nubs (almost pins) where the write-protect pads would have been, and through my testing with a multimeter, they are in fact the write-protect pads! Or nubs/pins. Bridging these with a little bit of solder will have the same effect as the answer.
If you don't trust that, then you can also try soldering a wire to the bottommost pin of the SD card slot (where bottom means the slot is facing your right, and the write-protect nubs are to your left), and then soldering the other end to ground -- in this case, the solid metal casing of the slot. I would recommend soldering to the bottom edge of the slot where there's an overhang of metal, since there's not a lot of clearance on the top of the slot when the whole thing is closed up.