It sounds to me like your 9600 is dropping into Open Firware on boot with the output directed to a serial port. You could try connecting another Mac and using something like ZTerm to monitor the serial console. You could also try to telnet into it over serial connection. Apple should have directions on their website for both these things.
Once you do that, make sure you do:
setenv auto-boot? true
You might also want to set the input device to your keyboard and your output device to your screen (trickier given the PCI card video setup). In fact, your input device might already be the keyboard, so it might be worth a try to wait a bit after you start it up and then type this on the keyboard:
setenv auto-boot? true
reset-nvram
reset-all
You also need to re-bless your OS 9 System Folder. I don't know if that can be done from Open Firmware. You may need to remove the hard drive and put it in another Mac to do it. But re-blessing in OS 9 is easy: Just drag the Finder out of the System Folder to your desktop, then drag it back in. Once you see all the fancy system icons show up, you've re-blessed the System Folder. In OS X, look into the "bless" terminal command.
I think XPostFacto puts a special Forth script on your hard drive so that when Open Firmware starts the boot process, it reads this script and tries to load OS X. It's neat when it woks, but it sucks when it doesn't.
For the record, I recently had this problem with a 2400c when I tried to install OS X. It would boot into Open Firmware (with the LCD backlight turned off - that's fun). A "bye" command loaded the Open Firmware script to load OS X, the Mac rebooted (after the script was read, I suppose), and ended up right back in Open Firmware. auto-boot? was true, and the reason it was in OF was because OF rebooted that the requested boot partition wasn't bootable. Catch-22 with no fix, or so it seemed. I managed to boot into SCSI Disk Mode ("bye" from OF while holding down Command-S) on a 9500, blessed the OS 9 System Folder, and rebooted just fine into OS 9. Back to the drawing board for OS X, I suppose.
Peace,
Drew
Once you do that, make sure you do:
setenv auto-boot? true
You might also want to set the input device to your keyboard and your output device to your screen (trickier given the PCI card video setup). In fact, your input device might already be the keyboard, so it might be worth a try to wait a bit after you start it up and then type this on the keyboard:
setenv auto-boot? true
reset-nvram
reset-all
You also need to re-bless your OS 9 System Folder. I don't know if that can be done from Open Firmware. You may need to remove the hard drive and put it in another Mac to do it. But re-blessing in OS 9 is easy: Just drag the Finder out of the System Folder to your desktop, then drag it back in. Once you see all the fancy system icons show up, you've re-blessed the System Folder. In OS X, look into the "bless" terminal command.
I think XPostFacto puts a special Forth script on your hard drive so that when Open Firmware starts the boot process, it reads this script and tries to load OS X. It's neat when it woks, but it sucks when it doesn't.
For the record, I recently had this problem with a 2400c when I tried to install OS X. It would boot into Open Firmware (with the LCD backlight turned off - that's fun). A "bye" command loaded the Open Firmware script to load OS X, the Mac rebooted (after the script was read, I suppose), and ended up right back in Open Firmware. auto-boot? was true, and the reason it was in OF was because OF rebooted that the requested boot partition wasn't bootable. Catch-22 with no fix, or so it seemed. I managed to boot into SCSI Disk Mode ("bye" from OF while holding down Command-S) on a 9500, blessed the OS 9 System Folder, and rebooted just fine into OS 9. Back to the drawing board for OS X, I suppose.
Peace,
Drew