I think the CD-ROM drive on this is fucked, which will make reinstalling the OS on a replacement hard drive interesting (this is pre-FireWire, so no target disk mode). Because I am a normal person, I’m tempted to use the G4 Mac Mini as a Netboot server.
INCREDIBLE UPDATE, the CD-ROM is not bad, there’s something wonky about the keyboard and/or the software controlling it. I’m able to boot to the restore disc if I plug in a different keyboard!
I thought to do this because I got a very similar error back when I was playing with hacked OS 9 on the Mac Mini. The solution was to use a different keyboard and mouse.