PowerMac G5 (Early 2005) does not boot

[catull]

My PowerMac G5 is a dual 2.3 GHz PPC, 300 GB hard disk, 4 Gb RAM running OS X 10.5.5.

I added a new SATA Hard-disk, installed Ubuntu 8.10 PPC64 server on it, configured it for dual-boot Linux | OS X.
I was only able to boot into OS X once.

I can mount the OS X partition under Ubuntu, navigate the file-system, create files etc.

When I boot OS X in text mode, it hangs soon, displaying "Still waiting for root device" forever, after the line that says
"[HCIController][configurePM] power parent ready after 1 tries"

I tried to access the hard-disk in Target mode, hooked it up to my wife's MacBook Pro, hoping to run Disk Utility on it; no luck. I tried both the fire-wire plug in front of the desktop and the one in the back.

The hard-disk OS X used to boot from is okay, just not bootable anymore.

Any advice how to fix this ?


Regards,
--
Catull