Hello, I currently have an issue with my iMac. For some reason, the screen does not turn on. I know it's not the backlight because nothing is visible on the screen. Other than the screen, the computer works fine. When I removed the screen to see if the problem was a loose cable, everything showed up just fine on my external monitor. I know the computer detects the screen because when I turn on the computer with the external hooked up, the desktop is expanded across both monitors. Also, all 4 LEDs are illuminated on the logic board. Can it be something as simple as the cable needing to be replaced? I believe the LED board can be ruled out since the screen doesn't turn on at all. Is this a fair assessment? Thanks in advance for any help .