IMac G3 won't update to Mac OS X 10.2 or 3?

I've never worked on a G3, but if the optical drive is bad, try:

1) connecting an external optical via Firewire, or

2) connecting to another PowerPC in Target Disc Mode via Firewire,

and boot from the install disc in one of those devices.

I believe even if you use an external optical, you have to use a firewire cable, not USB. Sorry!

I recently bought this Firewire cable from OWC - it's super cheap right now and I think it came in around a week.

I went through something similar with an iMac G4 awhile ago--here's the thread. Best of luck!

"I have heaps of upgrading disks e.g 10.3 Install disc, 10.4 and 10.5 and more. USB do not work on this one for some reason."

As you have discovered, the computer won't boot from a USB-connected optical drive. You can connect a CD-ROM or CD-RW drive via USB to read/write CDs, but you can't select that drive to boot the computer. Upgrade disks won't provide a means of installing their versions of OS X, unless the prerequisite version of the Mac OS is installed. There is no upgrade path to OS X from OS 8.5, via upgrade disks. Model-specific Restore disks won't install OS X on that iMac either. You need a retail/universal installer disk (Jaguar or Panther), as well as a working internal optical drive. Tiger isn't supported because it requires onboard FireWire, so Panther is the newest supported version of OS X. Additionally, 32 MBs of installed memory will never be enough to run OS X. Realistically, you should have at least 256 MBs of installed memory as a minimum.

"And I don't have a firewire cord for target disc mode."

The 233 MHz G3 iMacs (Rev. A & B) do not have onboard FireWire ports, so Target Disk Mode isn't an option.

Boot up the machine and see if you can read from a cd. If you can, you know you do not have the correct media.

Try using a cd drive cleaning cd.

Robert

First off, the 233 Mhz iMac can barely install 10.2 or later.

It must have its PRAM battery replaced first with a fresh one.

Its RAM must be upgraded to 128MB or higher.

Next it must have its firmware updated while booted into Mac OS 9.

Replace the internal optical drive with a working one if the internal one is broke.

http://www.macsales.com/ offers internal drives for those machines.

Here's the tip on upgrading the firmware

https://discussions.apple.com/docs/DOC-2125

Once you have upgraded the firmware you'll need a copy of the retail 10.3 installer and apply the 10.3.9 combo as this tip explains:

https://discussions.apple.com/docs/DOC-2831

Next it must have its firmware updated while booted into Mac OS 9.

No, the tray loading iMac's came with 8.x so you can update the firmware with 8.x. I believe you can run 10.x without updating the firmware.

Updating the firmware was important for slot loading iMac's.

Robert