Assuming it is not hardware but soft settings...
1) Check and make sure that your TV does not have the timer set.
The Timer feature allows you to set a day and time for the TV to turn on automatically and the device and channel to display when it switches on. If the TV is already on at the requested time, the TV automatically tunes to the channel you designated in the Timer menu.
When the Timer turns on the TV, the following message is displayed: "Press a button for the TV to stay on." Press any button on the remote control within five minutes if you wish the TV to remain on.
Note: The TV clock must be set before you can use the
Timer feature (see preceding page to set the clock).
Press down arrow / up arrow to enable or disable the Timer.
2) If not working, try SYSTEM RESET. Press SYSTEM RESET button on the front panel with pointed object (e.g. straight paperclip). TV turns off, green LED flashes for about 1 minute. When it stops flashing turn the TV on again. All settings other than Parental Lock need to be set again using the manual.
3) TV RESET. If all else fails for soft error. Your manual describes this last resort for soft type error. It could be hardware problem needing more expertise.
Manual can be viewed on a computer at