Use a spudger to pry the fan connector straight up off the logic board.
It is useful to twist the spudger axially from beneath the fan cable wires to release the connector.
The fan socket and the fan connector can be seen in the second and third pictures. Be careful not to break the plastic fan socket off the logic board as you use your spudger to lift the fan connector straight up and out of its socket. The layout of the logic board shown in the second picture may look slightly different than your machine but the fan socket is the same.
The camera cable connector is not secured by any locking or snapping mechanism. Hence, Apple sticks a small strip of black plastic with adhesive applied to the side facing the logic board behind the camera cable connector to keep it in its socket.
When moving the strip (cable retainer) out of the way, be sure not to break any surface-mounted components off the logic board.
Hold the end of the cable retainer down with one finger while you use the tip of a spudger to slightly lift the other end and rotate it away from the camera cable connector.
Disconnect the camera cable by pulling the male end straight away from its socket.
Pull the connector parallel to the face of the logic board, not straight up.
Use your fingernail to flip up the locking flap on the ZIF socket for the keyboard ribbon cable. The locking flap is located at the opposite side of the socket compared to the keyboard ribbon cable. Hook your fingernail under it and carefully lift it up vertically.
Do not attempt to slide the keyboard ribbon cable out of its socket before you have unlocked the ZIF socket. Ribbon cables are fragile and excessive force will easily break them.
Use the tip of a spudger to slide the keyboard ribbon cable out of its socket.
Seven 3.3 mm T6 Torx screws securing the logic board to the upper case.
Two 8 mm T6 Torx screws securing the DC-In board to the upper case.
Do not remove the logic board yet! There are components on the underside of the logic board attached to the the upper case that must first be disconnected.
Carefully lift the logic board assembly from the left side and work it out of the upper case, minding the port side that may get caught during removal.
If the heat sink appears to be stuck to the logic board after removing all eight screws, it may be helpful to use a spudger to separate the two components.
When reinstalling your logic board, don't forget to apply a new layer of thermal paste to the face of each processor.
Do NOT pull the subwoofer cable up. It pulls out — to the side. These instructions just ruined the motherboard as the weak subwoofer connector pulled off the motherboard, when it should have been pulled out to the side. Thanks a lot. Several hundred down the drain.