Joseph: With a “newish” fridge we use velcro strips to keep the fridge and freezer switches covered on Shabbos and Yom Tov and removed afterwards. (Two small strips of the “hook” side stuck one above and one below the switch, a long “loop” side velcro that gets raised to connect the two velcros and keep the switch pushed in so it’s off, or lowered when we want the switch to function as usual.)
It’s not a perfect system, and the velcro may need to be replaced occasionally. If something goes wrong, a non-Jew will need to be called to help out.