[SOLVED] yaboot help on failed hardy upgrade, help getting to prompt

[Kilz]

Hi Hi
I feel a little out of my knowledge area so I thought to ask for help.
I help out as the school my daughter goes to by being its it department. Since its a school attached to a church we have a low budget and Linux is perfect.
While I have a great deal of knowledge about Ubuntu, sadly I know nothing about running it on a mac. Someone donated a older PPC tray cdrom imac and I was happy to see Xubuntu already installed. Sadly it was Dapper drake. All the other pc's (3 total) run Xubuntu Hardy. The cdrom is broken so I couldn't do a fresh install, and I cant start over. After doing a search I found the fix to getting an upgrade going and let everything upgrade.
On reboot the screen goes white, and then black, and stayed black. I found a thread that helped a little when

Linux nosplash video=ofonly

is booted it doesnt go immediately black. I can see the loading screen. The loading line goes all the way until the screen usually changes to the login screen then goes black. I have a feeling its a xorg.conf problem. But I have no idea how to get to a command prompt to fix it, or what the fix would be. In grub I would boot into failsafe and the prompt would be there.

Thanks for any suggestions in advance.

First edit.
Ok some progress, so that anyone else running into this knows

Linux video=ofonly single

Brings up the rescue menu, including a root prompt. Now I am sure its a xorg.conf problem. I also found out that the imac has ati graphics.

Edit 9-14-08
After I got the xorg.conf working I had to remove the video=ofonly because with it the desktop was slow and had corruption when the windows were moved.