If only I'd read this thread this morning!
My motion sensor died Monday night - which incidentally shows how much the family have got used to ST, as there was much stumbling down the stairs in the dark. The motion sensor covers the stairs and turns on a Hue light to 20% at night - nobody thought to just turn the light on manually with an off/on motion on the switch right below the sensor
Anyway, I bought a two pack of Energizer batteries a month back because the multisensor in my Fridge needed one, and they both use CR2450.
Multisensor is working fine with the Energizer, but I put the same cell in the Motion and.... nothing. Dead. "Bother" thought I, "I'll have to buy a new sensor".
Opened it up and noticed that the vertical prongs are really flat and low - almost looks like they've been bent back too far. Thought it might just be a poor contact so tried to bend the prongs out and..... PING. They snapped off at the bend.
In fixing it with the spring out of a ball point pen ("screwed down" over the remaining prong), it now sits much higher and sticks out further - and actually works with the Energizer!
So, if you've stockpiled Energizer CR2450 cells, then just get some ballpoint pen springs and get modifying