Did you get the bolt shaft out?

If it was me, I'd get a �10-15mm diameter carbon cutting disk about 0.5-1mm thick for the dremel and cut a vertical slot in the end of the bolt shaft. Try to keep the slot (groove) edges nice and sharp.
Then using a smallish flat head screw driver knock softly in the side of the slot to try and turn the shaft anti-clockwise to unscrew it.

If you can't get such a small cutting disk, find a dental laboratory and go and bum one there.
I used to be a dentist and have used above method to remove broken off bolt shafts (if they're not stuck too much).

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.