My Macbook Pro will not boot normally or in safe mode. My power cable lights up green when it is connected. Pressing the power button does nothing. However, if I unplug the battery and wait a few seconds, the screen will light up, the apple and the progress/status bar comes on, as well. The working indicator starts to whirl but when the status indicator gets about a tenth across the bar, the screen goes black. There is no hard drive sounds.
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.