I assume you mean it still says 'Booting OS….'?
That's what you see if no lcd driver has loaded. If it's actually showing some other Watchguard related information it must still be running the Watchguard OS.
After you have loaded the lcdproc-dev package you have to go the Services: LCDproc: page and select the driver, screen size and port. Then add some screens in the second page. Then lcdproc should start.
Steve