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.

The LCD temperature sensor is located on the rear of the display panel in the top right corner when viewed from the rear. It is under the black foil about 40mm (1 1/2 in) from the top edge of the panel.

Lay the display panel face down on a cleared surface ensuring nothing is under the panel that may damage it.

Carefully cut a small nic in the foil at the top right corner and gently peel back at an angle to expose the sensor. It will have a foam pad stuck over it.

Gently peel the foam off the sensor to reveal the PCB assembly.

The Sensor is held in place with a small adhesive pad so to remove it, gently pry it up from one edge with a plastic spudger or similar. I recommend NOT using metal tools here.

Disconnect the cable to remove the sensor

Quality Tip When installing the sensor, ensure the connector is well seated and you don't put the connector or cable under tension as this may cause them to separate after reassembly of the system

Note the routing of the cable. It runs up the right side of the display panel and under the edge of black plastic PSU guard adhered to the display panel

If you need to replace the cable, gently lift the right edge of the black PSU guard and carefully peel the cable off the adhesive backing on the guard.