Unplug the power before trying these options 
NONE of the options worked for me until I closed down, unplugged the power cord, replugged the power, then rebooted.
Complete success after that!
A HUGE THANKS to everyone who is kind enough to post in the forums. You saved my day.

NONE of the options worked for me until I closed down, unplugged the power cord, replugged the power, then rebooted.
Complete success after that!
A HUGE THANKS to everyone who is kind enough to post in the forums. You saved my day.
-Option-O-F, to enter the Open Firmware prompt. Type "Eject CD" without the quotes, and press return. The disk ought to eject. To Start into OS X, type "mac-boot" without the quotes. Press return, and the computer should start up.