With the LCD lifted, disconnect the LCD cable by pulling down.

The LCD cable is attached to the underside of the power supply; be careful where you put your fingers so you don't get zapped by a capacitor.

On reassembly, you may find it helpful to remove the power supply, reconnect the LCD power cable, and then reinstall the power supply.

Alternatively, the LCD power cable can be disconnected from the LCD, rather than the power supply.