how to unlock Hitachi 51F59 front panel

Hi, my projection tv Hitachi 51F59 one day my sister used the remote control to watch the tv, soon she turned on the tv, the tv turned black and no sound.  Is this meant the tv totally dead or still able to fix it? I download a manual, it said the screen got black out due to the front panel got locked.  Is there anyone able to tell me how to unlock the front panel or reset the front panel.  I followed all the instructions to unlock the tv, but it doesn't work.  I would appreciate if anyone knows how.