There are five cables that must be removed. Two are standard plugs (highlighted in orange: the charging cable (top), and the speakers (bottom)) and three are locking ribbon cables (highlighted in pink (from left: power button, trackpad, keyboard)).

There are then four Phillips screws (red circles) that need to be removed.

Finally, the motherboard can be removed. USE CAUTION! Pull it up away from the machine slightly, and then slide it away from the hinge. It should come out easily.