MacBook pro not booting

Hi Everyone i have a 15" intel Macbook pro A1260 which is not turning on properly. i have tried the SMC and PMU resets but nothing seems to be happening. when i try and turn it on the hard drive and disk drive seem to function, but about 3 seconds later the power is cut?

Try another power adapter if you have one or can borrow it from someone. If that doesn't help, it's time to make an appointment with your local Apple store genius and have them look at it. (I'm assuming you tried to operate the machine from battery and the same thing happens?)

Regards.

Its definitely not the power adapter or battery. I remeber when i turned it off it sounded like the fans where still running a few seconds after the screen was off. If i cant get to work i will take to an apple store.