Hi , I bought an old 24” Cinema Display and it started to having this problem too. When I plug in the display port screen flickers for like a 2 or 3 times and dies off. Speakers and USB ports are working without any problems. Tried everything and none of the solutions worked for me. And I do not have the opportunity to go and replace backlight. So what I figure out is doing this appears to fix the issue! (1) Plug your mini display port and usb cable, (2) You will not see any image(obviously) set the Display’s brightness to the lowest as possible, (3) Plug out both usb and display port, (4) Plug only display port/after this screen will start to flicker like crazy, (5) Put your MacBook, Mac Mini … etc. to sleep mode, Wake up your system and you are good to go! At least this is working for now for me. Set brightness again to what you want it should be OK now. I know this is an old thread but maybe someone who has this will see and maybe it will work. Regards.