This guide will have you remove the upper case using a gamebit screwdriver and then in order to reveal the ribbon to the system from the controller port you will have to remove the reset button. This process will require only the gamebit.
Remove the six screws located on the underside of the system using the Gamebit 4.5mm screwdriver.
Carefully flip the unit back over.
Locate the seam. Lift and separate the upper half of the case from the lower half of the case.
Lift the right side of the eject lever out of the housing.
Pull the metal bar out through the right side of the eject lever.
Lift the controller ports out of the housing, this should be done without much force. Take note of the location of the ribbon cable connection.
Carefully remove the ribbon cable from its port.