Unlike the Nintendo DS which had several different custom firmware carts made for it over its lifetime, the Nintendo 3DS has been pretty resilient to piracy. The Gateway 3DS cartridge is the only cart that lets you play pirated Nintendo 3DS ROMs and even then you need to have a Nintendo 3DS on ancient firmware and a single ROM per cartridge. Despite these limitations, people are buying them and quickly discovering that the pirates have employed their own anti-piracy measures.
Originally reported by Eurogamer, it seems as though the developers behind the Gateway cart have added code in a recent update that functions as a killswitch that will brick the users console if any code is modified within the launcher. Many users found this out the hard way when attempting to circumvent the 3DS region locking using the Gateway cart.
You can read the rest of the story here if you’re so inclined, but this goes to show that you shouldn’t trust those whose aim is to support piracy.