So this is fun... I ordered a new carbon monoxide detector to, you know, save our lives. Stuck batteries in then wandered off to find some screws.

Came back, and it was warm n smelt of burning.

Batteries felt *hot*

Managed to ping 2 out, and then the third one burst, spraying me with hot battery innards.

Looks like it was probably here, phone doesn't do it justice but the board's bubbled and disformed.

Put it back together ready to return, but have cut the wires so that they don't do a quick power on test and then sell it on to someone else