Dell Precision 390 Blinking Power Light

Hi,  whilst trying to install a new mouse the computer restarted.  and niw it wont turn back on, the power light is continously blinking amber and no mater how I press the button it will  not turn on.  Unfortunatly i am unable to locate the full manuel and only have the quick refrence guide which points to Power Management in the full manuel. I have tryed leaveing the unit unplugged but as soon as I plug it back in the blinking continues.

Can any one suggest a solution??

Thanks in advance

Gareth:emotion-43: