Stripped Pivot Screw

I was trying to clean and lube this knife a couple years ago and ended up stripping the head of the screw, ended up tightening it accidentally and the blade is now stuck shut. I tried using a dremel tool with no luck then tried soldering a driver bit to the screw but that didn’t work either. Any advice to remedy this situation?

I was trying to clean and lube this knife a couple years ago and ended up stripping the head of the screw, ended up tightening it accidentally and the blade is now stuck shut. I tried using a dremel tool with no luck then tried soldering a driver bit to the screw but that didn’t work either. Any advice to remedy this situation?