Chosen Solution
I have a rather strange problem. I recently replaced my screen but in the process must have damaged something as the backlight began to flicker. I then replaced the display cable and the isight cable (which includes the power cable). This did not resolve the issue. Finally, I replaced the LED display driver board and now, the backlight will not turn off. Ever. As soon as there is a power source (power or battery) the backlight turns on, even though the computer is turned off. When I boot the computer, it boots normally, with the screen functioning normally. When I power off, the backlight remains on. I put my original faulty led driver board back in, and the backlight started flickering again. Put the new one in, the backlight won’t turn off. Did I just receive a dud driver board? It seems very strange that the screen always stays on, even though the computer is off. Any other possibilities?
I would say yes that you received a faulty driver board. I’d put money on that, not my life. With the flickering problem on the original one and now the new one won’t turn off there may be some other problem - on the logic board. On the Apple LED backlight system the voltage for the backlight goes up the LVDS cable and the driver board acts as a switch to give the LEDs that voltage. The driver board amounts to a 5 volt switch. I’d return the driver board for an exchange or refund.
