Apple PowerMac G5 auto-boot set to false, no video, help!

[dag219]

I did a stupid thing. My Apple Powermac G5 was not responding to any key combinations on startup, like command-opt, or even just opt, ...so in a terminal window, I reset the nvram auto-boot? variable from true to false. Now the system doesn't boot properly, no video. The keyboard combinations never worked anyway, so I can't even use it, ...but I don't know why. Before the video stopped working, the input devices were correctly set to mouse and keyboard, ...so I don't really know how to get the keyboard to function properly. Any clues out there??