15" MacBook Pro not booting up

My 15" MacBook Pro is not booting up. When I press the power button, it makes the initial start up sound and then nothing shows up on the screen. If I close the laptop after that, the power light near latch blinks as if in sleep mode. It sounds like a fan is on. I can turn it off by holding the power button down and I can hear something powering down. The battery indicator lights on the battery look like it's fully charged, and the power light on the adapter is green. I'm not sure what I should try next. Anyone have any suggestions.