I currently have a MacBook got it around 3 or 4 years ago. It worked perfectly fine, until one day for no reason I turn the mac on and the screen goes black . The mac symbol appears along the with loading circle, after a couple of seconds the screen suddenly goes dark. I can hear the computer is running, the volume sound as well if i press the volume key on the keyboard. I left it for a couple of hours charging, but the same thing happens. Everytime after the initial loading the screen goes black! Help!