Macbook Pro won't power up
I have had the same problem with my mac book pro. Maybe you could try booting from an external HDD?
In my case I tried everything from replacing the hard drive, reset PRam(hold cmd+shift+p+r right after pressing the power button), replacing the internal battery; all without success. So if none of those things won't work it's probably your motherboard having a serious issue. Only thing I could have done was replacing it.