OpenBoot Loading Problem

I am using a SunBlade 100 system and accidently set a new alias for keyboard, now when it start it gives the following error,

The selected input device has no read routine. Keyboard not present using ttya for input and output.

Now i cannot execute any commands on the OBP and i just gets stuck on after printing this message.
I have tried Stop + N to reset the nvram parameters but it doesnt work.
Any suggestions would be helpful.

Use the serial port.

I connect another solaris system using a serial cable and correct the nvram parameters . Thanks for the suggestion

If you can't do a Stop+N, this would be the workaround.
When you hard-reset the system, you will notice that the diagnosis LED will blink 3 times, once the 3rd blink is done, press the power button twice and this will cause the change to NVRAM chip variables to default settings. Fyi