The display did not light up so I got a flashlight to view the display. There was a display that said the batteries needed to be replaced. I replaced the batteries with 2 Duracell AA batteries that state they are good until Dec. 2023. The display now just says "Off". I READ THE DIRECTIONS IN THE LITTLE BOOKLET THAT WAS BEHIND THE THERMOSTAT BUT IT DID NOT COVER THIS SITUATION. I tried depressing the up and down arrows for 3 seconds but nothing happens. Please advise.