(From: Alan (firstname.lastname@example.org).)
Hold down the menu key on the remote for 8 seconds to switch it out of that mode or back in again.
(From: L. Tankersley (email@example.com).)
Try pressing both volume control buttons on the TV at the same time and releasing. The demo mode should go off and the set turn off by itself. Turn the set back on and it should be back to normal.
(From: Bill A. (Lucy27@ix.netcom.com).)
Try pressing the "menu" button on the unit and keep it depressed for about 15 to 20 seconds. This should release the demo mode.