Beware: USB killer-hubs

A few days ago a friend told me he had a nasty crash. An externally-powered USB hub screwed up his motherboard on the laptop just after he plugged in the power brick. He even showed me that hub. A 10-port hub just like the one I got from china (DX or aliexpress – I do not recall). The only difference – he picked up his at a local shop for twice its actual price. So, once I got to my lab, I cracked mine open to have a look what the heck could deal such a damage.