I saw your question before but could not think of what it could be except loss of video, either due to power loss to the signal processor somewhere or a problem in the video signal area itself. As I couldn't find any schematics for it I thought it better not to respond with conjecture.
Then you said that it was working again and I thought OK either still a power problem e.g. a dry joint somewhere, again do not know where or a dry joint/loose connection in the video signal area.
The best that I can suggest is to see how it behaves from now on. If it fails again initially the only thing to do in the absence of any service manual or schematics is to go over it, with the power totally removed, using a strong light and a magnifying glass and see if there is anything that looks "suspicious" in the way of soldered joints, suspect components or loose connections. (check both sides of any circuit boards)
If it is working you could gently (stress very gently) start tapping with the plastic handle of a screwdriver or any other plastic /nylon implement (toothbrush handle)(and the other hand behind your back) at various places on the boards, connectors etc (keep away from the AC input supply area of the monitor) to see if you get a reaction on the screen, to try to make it happen and isolate it to a particular area. Use a mirror facing the screen so you can see what's happening from the back of the monitor.