My father has recently bought me a new Lenovo Y550 from US. It was working well for nearly 2 weeks and after that it slightly getting issues regarding the power up. When I press the power button, the LED in the laptop glows but nothing will show up on the screen. I can also hear the sound of the processor. After this I wait for several minutes by disconnecting the power. Then I power up and push the button. Now it started working fine without any issue. So what happened at the first time?