When I turn on my Macbook the screen turns on for a second, then goes dead and continues to boot up. Once it's fully booted up (I can sort of see my desktop when I point the screen to my light), the Macbook goes to sleep. When I try to wake it, the screen is still off and goes back to sleep in 5 seconds. I know the LCD screen isn't broken because it does turn on for that second when I boot up. Plus, it doesn't explain why the Macbook goes to sleep. Is it be the logic board?