We had our C720 for 4 years it was doing fine until yesterday. I was doing my essay when the screen began to glitch than it would go back to normal but the mouse wouldn't move. So I decided to press the power button to restart and it didn't work neither and in a few seconds the whole screen went black. I just decided to leave it alone for a few hours and nothing I thought I should just charge it and the charging light was blue so I knew it was fully charged so I press down the power button but this time the blue light came on but it went off so I pressed it and again same thing. So today I gave it another shot and it happened again so I decided to hold down the power button and it came on and the screen went black but this time the blue light that indicates when it's on will not turn off. Unless you hold down the power button but it'll come back on by itself without the screen being on just still black. I went and unscrew the screes in the back and unplug the battery and plug it in and the blue light will flicker on and off and just stay on. I don't know what to do is it the screen that's mess up or the whole laptop. Thanks for the help I really appreciate.