Quoting Shay Telfer <[EMAIL PROTECTED]>:

> >But dealing with the logic board will require both knowledge and the 
> >facility to use the correct solder techniques.  It's not like the 
> >old days.
> 
> Ok, so now I'm concerned.
> 
> I'd suggest that in all likelihood Antony doesn't need to resolder 
> the machine, get a new motherboard, or even wave rubber chickens 
> around.
> 
> First, try booting the machine with an external monitor. If that 
> works, boot it into 9 and install the firmware patch.
> 
> Alternatively, if you feel comfortable with it, disassemble the 
> machine so that you can access the reset switch on the logic board, 
> and press it. It's a small circular rubber button inside o square 
> housing. A picture of a similar reset button on a different model of 
> machine is located at
> 
> <http://www.zone6400.com/manual/files/CUDA.html>
> 
> If not, do whatever else you want to it :)
> 
> Good luck,
> Shay

It is possible to get out of this firmware problem if that is infact what it is.
Booting from and OS9 CD won't work, the firmware updater won't run in that 
environment.
You need a HD with OS 9 installed on it only, no hint of an OSX bootloader.
An external monitor as suggested previously.
Install the HD on the iMac ide chain.
Start the mac and apply the the firmware update from the OSX cd.
Install your HD with OSX installed on it.
Get out rubber chickens if desired.
Gordo