Having had the battery charger on for a full day, tried to start the Mantis (to look for mice! No, really…). Alarm LED was working. Second hand on clock moving, so definitely power. And…

Nothing. Bugger. 😫 The mice are happy though! 🤣

So something is draining the battery within a day, or the battery has had it. (Not expected as Optima Red Top, less than three years old). Ho hum. 🤔