Changed Startup to OS9 on Power Mac G4 MDD FW400 - Stuck with Blinking Question

[GuiBer]

Well !
To clean-up all old NVRAM parameters, I suggest you to do :
At the boot, hold down Command + Option + O + F until you've arrived at the Open Firmware prompt;
To reset the system NVRAM, enter 'reset-nvram';
To reset the machine, enter 'reset-all'.
The Mac restarts, hold option key to set the boot drive (OS X) and in the System Preferences set the correct date and time.

Happy computing, with a Mac of course !