Your computer is equipped with four diagnostic lights, which are labeled "A," "B," "C," and "D" on the back of the computer. Each of the four lights can be yellow, green, or off. When the computer is turned on or restarted and it is functioning normally, the lights flash during POST. After the computer starts, the lights remain green to signify normal computer operation.
If a malfunction is detected and the computer fails to start, the lights display a code that identifies the problem. Write down the diagnostic code displayed and tell us what color each lite is or check it out
here...
check your Power Button Light Code
Off Power is off.
Blinking yellow ...The computer is in its first state of starting up. If the light remains in this state, check the power supply.
Steady yellow The computer is in its second state of starting up. If the light remains in this state, be sure that the microprocessor is properly seated.
Steady green The computer is in a normal operating state.
Blinking green The computer is in a low-power state.
try this to get to your bios...
Turn on your computer... When F2 Setup appears in the upper-right corner of the screen, press F2
if you don't see anything in the upper right on the screen start tapping F2 about 2 seconds after pressing the power button to turn on the computer...it may take several try's to get the timing right..
if you can't even get to the bios you will at a minimum have to replace the motherboard battery...its about the size of a nickel and costs about $5.00