PowerBook G4 won't boot up

Hello! I have a 15 inch PowerBook G4, and I was trying to Re-Run the OS X Setup Assistant. After rebooting the laptop it took me to the grey boot screen and it seems like its booting but after 2 minutes of showing the apple logo and the grey spinner it just shuts off.

I have tried to restore the login screen using:

touch /var/db/.AppleSetupDone

but no luck.

I don't have a leopard disc. Any help appreciated!