Sony tv kdl 42ex440 Turn off demo mode - Sony BRAVIA® DAV-HDX576WF Theater System with Wireless Speakers

Have you tried to do a "reset" ALL modern electronic items often get "locked up" and unplugging them from the wall will often get them going again. Unplug for at LEAST 30 seconds--then try again. If this does not help--the SMPS board may have failed on you. A good repair shop may be able to repair the board instead of replace it.

Turn on your Sony Bravia.

Press and hold the Up Arrow button on the remote control

Press the Power button on the TV while still holding down the Up Arrow button. The TV will turn off and then turn itself back on.

Release the Up Arrow button. Once the TV turns itself back on, it will restore your Sony Bravia to its factory settings.

http://www.ehow.com/how_5855646_reset-sony-bravia-tv.html

Make sure the TV is set for home mode. Information for doing this is included on page 11 of the owner's manual. Click here to view or download the owner's manual for the TV. ON the remote control press the up arrow and hold it in. Press the power button on the TV itself twice. Hopefully this will correct the problem.

the problem of your TV is the demo button...when the button is defective it remains on contact so that it comes to demo mode automatically..

you need to do is replace the button of demo or menu in your TV

Here'show to turn off the demo mode,

Power ON the television
(Use remote Commander)
1.Select "TV" mode (not AV, demo mode can't switch offwhen you are in AV)
2. Press the "home" button on the remote.
3. Select "settings"
4. Select "set up"
5. Scroll down to "factory setting" and restore them.
6. When it asks home or shop display select "home".