My Mini powers itself down before it finishes booting. It's a 1.25Ghz G4 Mini, so it's a few years old. As of the last few days the computer turns itself off. So I push the power button and I get as far as the grey screen and I see the circle logo rotate and I can hear the disk heads seeking if I place my ear near the Mini. But before the OS boots, while the screen is still grey the Mini powers off. It does this with the recovery DVD in the drive too. Either way it never boots Is there a way to diagnose this?