Why won't my Vizio tv model V505-G9, stay on?

Hi,

So I have a Vizio TV ( model # V505 - G9 ) that turns on for 1-2 sec then turns off. I can see the screen says there's no device connected. So I know it's not the back lights. I tried switching outlets & secured cables, tried unplugging it and holding the power button but nothing's working. Haven't opened it up yet tho. Any help is greatly appreciated.