PowerBook G4 Problem: HELP

Well i dont have my charger with me and i only had 30 min. left on the battery when i started to put a song onto garage band, send to itunes, convert to MP3, and then host it on the internet. When i got to the hosting part supposedly i had 17min. left on the battery. I got on the website and starting hosting it and the computer went to sleep. I just let it sit there asleep since it doesnt use as much battery and i needed this hosted.

Anyway, the screen wont come on and i cant even get it to turn off. The light on the front of the screen latch is fading from unlit to lit. What the heck is goin on and how can i turn this off?!?!?