See if it will start from the optical drive. The iBook G4 has no PRAM battery, it's function is built into the main battery. There is a capacitor that holds a 20 second charge when the main battery is pulled. If it fails to start from the optical drive, unplug it, remove the battery and hold the start button down for 10 seconds. This failing please let us know and we'll proceed. This machine will boot from system 9 or 10 by holding down the option key on start-up, if it's installed. The X on the drive means that either there is no bootable system or the hard drive has failed. If it boots from the installation disk go to the second page pull down menu to Utilities -> Disk Utility and see if it sees the drive, if so then try to repair it.