The last component you must remove to replace the Motherboard, is the Body-Neck adapter. This connector controls communication between the Guitar Keys and the body of the Guitar (Strum Bar, Whammy Bar, etc).

To remove the Body-Neck adapter, simply unscrew the one 12 mm screw which holds it in place, using a Phillips Head 0 Screwdriver.

Lastly, carefully lift all three components you have just unscrewed by the corners. The Motherboard will come off with little force.