Inspiron laptop

My inspiron laptop have some problem.
"When you press the power button, If your laptop powers on, the lcd panel is pitch black blank screen, not even back light power, no dell startup screen, you hear the fan spin up, you hear the hard disk spin up, in this state one of the 3 LED lights blinks for 7 seconds (I think numeric keypad), and then if everything switches off silent. The only LED on after that would perhaps be the battery charging indicator.