This charger claimed that both my batteries are faulty, which seemed a but of a coincidence, so I suspected the charger instead.
Here's a picture of the board:
I'm puzzled by the largish round holes, both in the middle of the board, and diagonally towards the left, in the proximity of the labels for C13 and R43. In both cases, they're where I might have expected to find anti-tracking slots, but holes are not going to achieve much.
Towards the centre of the board, R4 and R3 seem to have been deliberately placed where they might be subject to tracking if it occurred.
Anyone seen this kind of thing before?
BTW, for those in Australia, this is an Ozito PXCG-030.
I haven't been able to determine whether it's faulty yet. No obvious smoked has escaped. It puts no significant voltage onto the output pins, but it contains a microcontroller, and also has a communication connection to the battery, so it seems entirely possible that it won't supply charge until it determines that a battery is connected.