Perhaps you should replace the battery on your machine. A bad battery can cause startup problems on some machines.
I have not seen this error message. I search on the Internet for this kind of stuff & do the magic with my fingers crossed.
Your title has set default, but the command is set-default
You should get something like unknown command. You sure you didn't put an extra space in the command somewhere. This isn't Unix. There is a set command if I recall correctly. There are no spaces in set-defaults
Here is what I post on this topic. Try the other commands & see if they work.
Sometimes if volumes don't appear in Startup Manager (what you get when you hold down the Option key at startup), you need to reset the Mac's PRAM, NVRAM, and Open Firmware. Shut down the Mac, then power it up, and before the screen lights up, quickly hold down the Command, Option, P, and R keys, until the Mac has chimed twice more after the powerup chime.
Then, before the screen lights up, hold down Command-Option-O-F until the Open Firmware screen appears. Then enter these lines, pressing Return after each one:
reset-nvram
set-defaults
reset-all
"The reset-all command should restart your Mac. If so, you have successfully reset the Open Firmware settings."
http://support.apple.com/kb/TS1812?viewlocale=en_US
Should this fail...
Try taking the battery out for 10 minutes. Put battery back in. Cross fingers. Power the machine back on.
How to eject a cd from the internal cd drive:
eject cd
List of devices:
devalias
List of variables:
printenv
More than you ever wanted to know about open firmware
http://www.firmworks.com/QuickRef.html
( nvram is the equivalent Mac OS X terminal command. )
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Resetting your Mac's PRAM and NVRAM
http://support.apple.com/kb/HT1379