I haven't been this confused for a long time... So. The USB can mount inside the broken installation of Panther on the iBook. Opening the Disk Utility that's on the installation USB (the one that's meant to be on the broken Panther is missing, and is a part of why it's broken), it says that the USB is bootble in the "Get Info" part of the Volume details.
The Boot selector (holding Option on startup) doesn't show the USB drive, and as far as I can tell, neither does Open Firmware. I blessed the Core Services folder with the bootX file, and that changed nothing. Actually, I can think of very few things I haven't done. - I've even tried two separate images (one ripped from a physical disc I once, but no longer have and one downloaded off the internet)
It is really starting to feel hopeless this is.
[doublepost=1530137810][/doublepost]Oh yeah, and I obviously recently bought this iBook second hand. There person I bought it from gave me the login details of a user account on the machine. If I navigate to "Install OS X" on the USB via the Finder in the broken Panther install, it asks if I want to restart from the USB. I click yes, but it wants an admin password that I don't have. I tried running passwd from Single-User Mode to change the admin password, but passwd doesn't do anything, and it appears the executable for passwd has been deleted from what is really turning out to be an extremely broken Panther.