My monitor went black, and the power switch just flashes.

Is your CPU working properly? if that the case, your monitor is in need of a service.
reasons for why a monitor goes blank?
Reason 1: Wetness
The number one reason why computer monitors go blank is - wetness. Believe it or not, when your computer monitor is exposed to humid air, sometimes water can condense and accumulate in the monitor. This causes the monitor to malfunction and go blank. I've had this happen to my desktop PC at least three times before. What you need to do is to leave the monitor alone for some time and allow the water to evaporate. That usually solves the problem.

Reason 2: Faulty Graphics Card
The next reason why your computer monitor goes black is due to a faulty graphics card. The best way to detect this kind of problem is to connect up a new monitor to your PC, then check if you have a blank screen. If you continue to have a blank screen, then it's likely your video card is faulty.

Reason 3: Faulty RAM
This one is less obvious and less common, but it can happen. You might sometimes get bad RAM modules which prevent your PC from booting up even to the basic BIOS startup screen. To detect this kind of problem is more troublesome, you might need to remove those RAM modules and insert them into another computer.

Reason 4: Loose Connections
Another reason why your monitor goes blank is due to loose connections. The connection from the monitor to the mains is usually a culprit, as is the connection between the monitor and the video card. Check those connections before you declare your computer monitor as faulty.

Reason 5: A Short Circuit In The Motherboard
And the final reason why your computer monitor goes blank? It's possibly because of a short circuit in the motherboard. This is the most undesirable outcome of course, as you might have to replace your entire motherboard. However, it's possible that this can happen - so keep your fingers crossed and hope it doesn't happen to you.
try this.
please rate my solution.
have a nice day.

HI, In have a 2004 Dell E17F2pb monitor. The screen is blank and the green power button on the monitor is flashing. When I hold the power button to turn the monitor on, the screen flashes on for a moment then goes blank again. Is the monitor trash?

Thanks,
Jamie

All of these answers are stupid. bcoz, every technicians conforming several times actually the problem coming from where.
checking in different computers and monitors, then only deciding.
so please send the remedies for monitor