I dropped my computer no more than 3 feet. The screen wouldn't turn on at first. I tried rebooting with pressing shift right after the power button, then I tried NVRAM restart. At that point I started hearing the booting sound (the chime), which I wasn't hearing before. But screen is still black (on but black). An SMC restart did nothing. Connecting the macbook to an external screen worked only in safe mode but not normal. Help?