The other day someone bought me a couple of Apple AirTags to look at. Apparently, they both stopped working after having the battery replaced a few days earlier.

Did both AirTags just decide to die at the same time?

Doubtful.

My first clue was that they both decided to die when the battery was changed.

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Were the batteries faulty? 

No.

In fact, the reason why the AirTags stopped working is because of a safety feature that some manufacturers are adding to their lithium coin cells to prevent them from being eaten and swallowed by children.

The problem: safety coatings

Button cells might seem harmless enough, but if swallowed they can cause serious health problems