How to troubleshoot a computer with Open Firmware Password enabled
If you cannot access the Open Firmware Password application and need to troubleshoot your computer by:
Resetting the PRAM
Starting up in Single-user mode
Starting up in Verbose mode
Starting from CD-ROM
Then follow these steps:
Start up into Open Firmware by pressing and holding the Command-Option-O-F key combination during startup.
At the Open Firmware prompt, type: reset-nvram
Press Return.
When prompted for your password, enter it and press the Return key. It responds OK.
At the Open Firmware prompt, type: reset-all
Press Return.
The computer restarts and you are now be able to reset the PRAM and startup in Single-user mode, Verbose mode, or from CD-ROM.