If you can get to the nut or the female part , put some heat on it with a tourch (not the bolt) and when you get it hot enough it will swell up somewhat and breake the bond with the bolt .Remove the bolt while the nut is hot - its kinda touchy though because you don't want to get any of the sheetmetal hot and warp it . Also , don't catch anything on fire , have a helper handy with some water. A little heat does wonders sometimes !
