Try a hot air gun, then a centre punch and hammer.
If that doesn't work, I can only suggest drilling through the stud, but needs a steady hand and good kit.
Start with a pilot hole, gradually increasing the drill bit size. Once you're out to the actual stud size, the nut should come away quite easily.
Good luck.
Clive
If that doesn't work, I can only suggest drilling through the stud, but needs a steady hand and good kit.
Start with a pilot hole, gradually increasing the drill bit size. Once you're out to the actual stud size, the nut should come away quite easily.
Good luck.
Clive