Inside a solar USB power bank with "short circuit" feature.

I was sent this solar powered USB power bank by someone who had been disappointed by its seemingly poor capacity. It turns out that was the least of the problems, with a big solder blob shorting one of the socket housings to the lithium cells positive terminal, resulting in a dead short when anything with the shell connected to negative was plugged in. (screened plug shells are common)
Fortunately there was protection on the negative rail, otherwise the simple act of plugging in a load could have caused the internal lithium cell to fail completely due to the high current flow.
These units are not in the least bit waterproof as some of the listings imply.