If a user performs this command at the Open Boot Prom (OBP)

     OK setenv disk-led-assoc 0 x y  (from infodoc 16735)

for the disk led association on an Ultra 450 
and they make a typo while doing so, they may get no display
upon reboot.

Power off the system.

Hold down the `stop' and the `n' keys on the keyboard 
simultaneously and continue to hold them down while
you power on the system.  Hold these two keys for at least
30 seconds or until display comes back.

This clears the bad entry, and the user can try again.