hey everyone used my macbook last night...shut it down normally....now when i switched it on in the morning i only hear the startup chime but there is nothing on screen(screen is on but is blank black). tried everything that is floating on internet including smc reset, but nothing helped. connected it to tv with hdmi. display appears on tv but i see boot screen stuck at 50%, still nothing on macbook pro screen. i clean format macbook and reinstall yosemite, still nothing on screen and boot screen still stuck at 50%. can you guys please suggest something.