Don't know if this is present on your machine, or if it will help,
but when trying to get OS X 10.1 to boot from the IDE drive on my
233MHz Beige G3 (OFW 2.01f I think), the Apple phone support people
told me to press the mother board reset button.  IIRC it is a tiny
switch between two of the PCI slots (or maybe between the slot and
board edge).  It looks like a big surface mount resistor or cap.

They never did get my problem solved, so I have 10.1 on an external
SCSI disk.  (It will not boot if I move it internally either.)
They said it would need to go on a test bench to go farther, and
I figure it works, just not as well as I'd like, but I'm cheap

In message <OF6EF1DD28.99026436-ONCA256C32.007EA0D9-CA256C32.007F8C42@au.ibm.co
m>, "Kevin K Woo" writes:
>Hi,
>
>      As the subject header indicates, I accidentally set real-base to
>600000 instead of F00000, and now my Beige G3 (266 mhz with OF 2.4) won't
>boot into Mac OS 9.1 or into the Open Firmware screen. I've tried
>unsuccessfully the following to fix my machine:
>
>      - Option-Command-P-R to zap the PRAM
>      - Option-Command-N-V to zap the NVRAM
>      - Removing the battery from the motherboard for 10 minutes
>      - Removing a 2inch x 2inch card from the motherboard for 10 minutes
>(I thought it *might* have been the OF card)
>      - I didn't find the hard power switch