iFixit

Use the attached black tab to pull the data display cable connector away from the logic board.

Remove the eight 12 mm T8 Torx screws securing the display panel to the rear case.

Lift the display panel from its left edge and rotate it toward the right edge of the iMac.

With the display panel still lifted, disconnect the four inverter cables.

During reinstallation, place the four inverter cable connectors in voids between components attached to the rear panel so the display panel will sit flush.

During reassembly, the order of the inverter cables is interchangeable within each socket.

If you are replacing a hard drive and have an extra set of hands, it is possible to reach in and remove the drive without disconnecting anything but the LCD temp and display connector in the previous step with the LCD in its propped position.

If necessary, remove the pieces of tape securing the hard drive/optical drive thermal sensor cables to your iMac.

Disconnect the optical drive thermal sensor connector from the logic board by pulling its connector toward the top of your iMac.

When removing this connector, it is helpful use your thumbnails to push the ears on either side of the connector toward the top of your iMac.

Remove the two fine-thread 7 mm T10 Torx screws securing the optical drive to the rear case.

Lift the free end of the optical drive slightly out of the rear case.

Remove the two 3.5 mm T6 Torx screws securing the optical drive connector to the optical drive.

Insert the flat end of a spudger between the optical drive connector and the body of the optical drive.

Twist the spudger to separate the connector from the optical drive.

It may be necessary to work from alternating sides of the connector until it is disconnected.