if you go to the manual and look on page 27 it shows a nice close up of the power switch connection
it is labeled "pwrbt" for "power button"....that is where the switch from the case plugs onto...and it doesnt matter on that one which way it plugs......and if you take the board out of the case what you will need to do is short these 2 pins together briefly with a flatblade screwdriver to make it boot