If you have one of these then you may wish to either stop using it or completely change the way you use it. At the very least, wear insulated gloves and make sure the unit is unplugged after use. Do not rely on the onboard switch.
There are safer units available that convert the incoming power to an isolated and current limited supply, but this one pretty much puts full mains voltage straight out.
The bizarre LED dangling through a ragged hole in the ungrounded case may actually be a crude FUSE! Because if the positive lead touches grounded metalwork there will literally be a dead short, with just the internal rectifier and the LED in series with the mains supply. LEDs do actually make surprisingly good fuses due to having a microscopic encapsulated bond wire. They do sometimes blow in half though... Sadly, the LED will not save you from electrocution. It takes much less current to kill a human than to blow an LED bond wire.
Technically speaking they could have made a marginally safer unit by putting a capacitor on each leg of the supply and limiting the current to a much lower level. Even high power resistors could have been used for that. It would still pose a shock risk, but with much less chance of being fatal. But for a proper reliability test on a faulty LED panel a higher current may be useful.
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