12V 15mm Distance Wireless Charging 5V 500mA Output 22mm Coil Wireless Transmitter + Receiver Power Charger Transfer (22mm Coil)

Just bought it and tested, worked as intended.

I connected the "square" board coil to a 12V supply and brought the "round" board receiver coil near it and an LED on the receiver lit up a few times. So I connected the receiver to a short LED strip and nothing happened at all. Now when the sender is connected to the 12V source it pulls the measured voltage down to zero. I suspect that the pair of devices I received were not fully functional, but due to the nature of the beast it's hard to tell. That was, what, a $13 fruitless experiment? Just trying to avoid drilling a hole in the back of a cabinet to add some very small low-level light strips inside it.