Macbook Pro power problem

[sdrawkcabssa]

I have read forum suggestions until my eyes have gone blurry... I've yet to see anything that has resolved my issue.
I have had no problems with my MBP until yesterday afternoon. Without warning it turned off. (It was charging at the time and there were no power problems.)
I closed the lid, and went on to something else, not having the time to mess with it. Later that evening I tried to boot it up... Battery showed fully charged by green LED on the power cord, I could hear the normal internal noises it makes when booting up, like the optical drive and the faint sound of the fans.... however, no keyboard lights and a completely black screen.
Thinking perhaps the battery wasn't up to snuff, I pressed the power button down to turn it off since the keyboard is non-functional... & tried to start it up again... this time with the power cord..... still nothing.
I have tried all rebooting suggestions, etc to no avail.
Could a defunct battery be causing this? But then, wouldn't it work with just the power cord hooked up????
I am so confused, ticked off & disappointed.
Naturally, it's out of warranty & Apple Care? Shoulda, Coulda, Woulda! Argh!
Suggestions?

[Giaguara]

It could, among a lot of other options.
Reset PRAM and PMU [see howto section of the forum for this], and then I hope you'll get it up and running again... what I'd like to see is what Console reported as the reason of the shutdown for the time it was powered off. There will be something in the logs, when you'll get it powered on again...
Do you have any external displays? Maybe those could show the image..