Brand new monitor failing?

I own an LG L246WHX-BN. It was purchased few weeks ago. I use the LCD monitor to play my Wii. There was once when I was playing Wii and someone came to use the hair dryer (1000W) that shares the same socket extension as the monitor. Moments later, the screen turned black. I could still access the monitor's menu to change signal (to HDMI or VGA). On top of that, if Wii was not feeding it with video signal, I was supposed to get a "No component signal" message from the monitor but I didn't. Now, it the monitor would turn black once in a while. In order to resolve this, I had to switch to HDMI channel and back to component to be able to view image again. When black-out occurs, the monitor's power indicator stays blue, meaning that it still stays on.

Could this be a backlight problem? Or could this be the cable's fault?

Unfortunately, I cannot test the VGA or HDMI signals because I do not own a PC (sad).

What are the chances of undervoltage killing the monitor? Anyone?

That is the most likely reason why the monitor failed. Turning on a hair dryer on any line will cause a sudden electrical spike on that line. So much so that apparently it was too much for the monitor which caused something inside to fail.

Since the monitor is new you should be able to request an RMA for a replacement. Do not mention anything about the hair dryer. Simply state the monitor stopped functioning properly.

Never, ever do that again.