Power Mac G4 Gigabit Ethernet - Won't Boot from CD

[iMac600]

400mhz Power Mac G4 Gigabit Ethernet. Just had a logic board replacement and needs the operating system reinstalled.

It won't boot from CD though. Disc in, every time it starts up it gets to the point where it would boot from CD but just spits the disc out.

Tried 3 optical drives and 5 OS discs, including 10.3, 10.4 and 9.2.2. Can't work out what the problem is.

Any ideas?

 

[iMac600]

For future reference, if your discs just keep ejecting rather than starting up, try disconnecting the keyboard.

I was using a PC keyboard which kept ejecting the drive on boot for some reason. Connecting an Apple keyboard solved the problem.