I wanted to change the boot logo for my Powerbook G4 so i used MacOS X to find the location. I changed it and had to change some permissions to do so. I then restarted the computer. It reached the grey apple screen and then the blue screen...then it stopped...and never continued to the login screen. if anyone knows how i could somehow force start the computer without resetting it and without losing all of my information that would be EXTREMELY helpful.
If you have another Mac nearby with a FireWire port, you can likely book the PowerBook in Target Disk Mode. Power it down, then hold the T button when you turn it back on until a FireWire logo appears on screen. You can mount it as a drive on another Mac, and restore the files you altered from your backup.
If you don't have a backup, you could at least use Target Disk Mode to make a backup of your data so you won't lose it when you restore the PowerBook from its restore CD/DVD.