1.Check if you set the time in the clock menu- on time, as TV will be switched on when the set on time reach.

Cancel the on time that you set:Setting-->Divice Preferences-->Timer-->Power On Time Type-->Off

2.Check if you set the time in the clock menu-off time, as TV will enter standby mode when the set off time reach.

Cancel the off time that you set:Setting-->Divice Preferences-->Timer-->Power Off Time Type-->Off

3.Check if there is no signal Within 15 minutes, as the TV will auto sleep under this condition. but This function is not available in all models.

 4.Please call service center when your TV not ok after above operation.