Did your TV come with two remote controls, and if so are both remotes incapable of turning off the TV.
When you press the power off button does the LED on the front light up to acknowledge that a button has been pressed.
If you press and hold the power off button for 5 seconds do you get the Restart screen.
I take it other functions on the remotes work as expected.
Do you have another Sony TV in the house (or perhaps a neighbour, friend or relative) that you can use that TVs remote to see if your new Sony will respond to the power off command from the other TVs remote.
If this is a very new TV have you contacted the seller to alert them to the problem, they may be able to help you
with a visit from an TV repair person to diagnose the problem and offer a solution.
If it is under 30 days old you can ask for a replacement TV or a full refund.
Unplugging your TV does not delete all your app passwords.
