Gen3 Nav error

My NAV is messed up and now when I turn it on I get a screen in Japanese with English text
that reads:
------
CAUTION

Error; System unable to access the program.

Incorrect program disk.

Please insert proper disk.
------
I saw a fix for this that involved pressing a momentary switch on the board inside the unit, but the Gen3 unit is simply one board with the DVD drive attached to a ribbon cable and no switches.

More details can be found here.
http://lexus-toyota-nav-trouble.blogspot.com/

any help is greatly appreciated.

I also posted a message for help from any Japanese members in the International forum but if anyone knows of any forums that may have more Japanese members (but in English) please let me know.

thanks.