20" Cinema Display has power, but screen is black….

Hi all,

I have an Apple Cinema Display (A1081) with the 65w power supply "brick".

I have been using this for the past few years with no problems, as an external display for my laptop (MacBook Pro with 10.7.5), everything works fine (turn on laptop, close lid, a few seconds later I just tap the bluetooth keyboard, or the mouse, and the display shows what's on the computer).

Yesterday, the display wouldn't come on (black!) even though it has power (the white light is on). I tried plugging, unplugging, restarting etc, and it did come on again once, but when the computer went to sleep the display wouldn't come back on. Now it won't come on at all.

When I have the laptop on, and I plug in the display cables, the laptop screen flashes blue for a moment and then the screen comes back to normal (which is what used to happen but the external display would also come on after the "flash" of blue on the screen...)

Is there any testing I can do to see what the problem might be..power, some internal component?
Is there anything I could repair myself?

Thanks for any help,

Alan.