How do you change the battery?

Find the back where the f/c button is. There is a little slot thing on the far end of the temp guide. Pry off gently using slot-head screwdriver. Pops off. Remove battery cover twisting with the rounded end of the temp guide or a large coin. It might be stiff to turn the first time you do it. Use a small plastic item, like a toothpick, to pry battery out. You want a 3v lithium coin 2032, label side up. Replace and twist cover, then snap the temp guide on, easy-peasy.