A suggestion:
With the tv on, press and hold the MENU button on the TV, while holding; use the remote (aimed at tv, of course) press MENU, 8, SELECT in that order.
If service menu appears, great.
If not, well, we tried.
To exit the service menu, press EXIT on the remote.
NOTE: When in the service menu, write down your settings before changing anything.
This way, you can go back to the original values if you screw things up worse than they were in the first place.
Write down your settings. You have been warned.