If your cabinet is like many, it's fairly thin sheet metal. I would get a cheap hole saw (it's like a real big dril bit, but hollow in the middle, used for making holes in doors for lockset installs) and drill a hole through the metal of the cabinet to surround the stuck screw.

Then you can take out the cabinet and later get out the screw with a pair of vice grips, or just cut off the screw with a hacksaw.

Does the screw turn or is it stuck solid? Is the head still in good shape or is it stripped?