Q: Mac G5 wont startup, freezes at startup and stays at a loading grey apple screen.  Help Please!

Gulp, but some things to try...

What shows if you hold alt key at setup, & how long will it sit on that screen?

Does it boot to Single User Mode, CMD+s keys at bootup, if so try...

/sbin/fsck -fy

Repeat until it shows no errors fixed.

(Space between fsck AND -fy important).

http://www.westwind.com/reference/os-x/commandline/single-user.html

Not impossible, but very unlikely, in fact the opposite is much more likely… preventing the loss of data.

To exit single-user mode type

reboot or macboot


hit enter & see if t boots up.

OK, not likely the Hard drive then.

How many drives in it, what all is connected by USB & Firewire?

What happens if you hold shift key at bootup?

Disconnect all but the mouse & KB & try it.

Was it the restart from Single User Mode you tried, or both that & shift later?

I'm not sure if restart might be for IntelMacs only, try macboot or mac-boot from SU mode.

Try booting in Verbose mode & see if you can read the last few lines it prints...

CMD+ v keys

Try Verbose mode on that one.