I have asked around and people I know have said the way they fixed a blinking power light was to turn off the PSU from the back, unplug it then press the pc's power button down for 10-15secs to kill the power to the motherboard.
Try this. Anyway you should always press the power button a few time when you have turn all the power off to rid any left power, like when you turn off a pc then by the plug and it takes 10seconds till the speaker and monitors lights go off.