laptop only turns on sometimes

i have the lg 15Z90S laptop and for the past few days it has only powered on sometimes when i press the power button. the power button light turns on every time i press it but the screen and the keyboard don't turn on. sometimes when i press the power button though it turns on and runs without a problem until i turn it off. the power button feels the same as always and the battery wire is connected to the motherboard on the inside of the laptop. any ideas what it could be?