Is the button itself physically stuck? (Use a pin or a needle, stuck into the part of the pin that's stuck in and lever it out against the bezel. Then smooth out any roughness you caused or it will get stuck again - use a sharp, small knife or boxcutter.) Or is it the switch that's under the button shorted (the button moves in and out as you press and release it)? In that case, it needs a repair shop and possibly a new motherboard.