What do you mean it will not boot up? Do you mean you press the power button and nothing happens? (No fans or beeps). Or does it not boot to Windows?
The comp starts to boot, then shuts down before it can finish to boot, then it surges on and off with all four lights flashing. The fan motor and mouse also flash in conjunction with the four flashing lights. There is no other response from the computer, and there is no other activity evident then the repeated flashing of the above mentioned activity. I have checked power cord and replaced, as well as checked the usb ports for any touching contacts that may have caused the problem, and found none.