I have a Laptop of HP Pro book 4420s. It's 4 years old. I think Battery is damage. Whatever when I hit the power from my house board the laptop power button white light flash(light is not solid at that time) for one time. After that when I hit the power button of laptop, the fan is run very fast and power bottom light is flashing very solidly for 1/2/3/5/..10 sec. After that it's gone off. And automatically again and again happened this situations. But Laptop is not started. If started it's working fine ,,very few of time it's off suddenly.