Xbox 360 had the reset glitch hack where if you powered cycled the chip at the exact right timing you could run unsigned code. It required a small mod chip soldered to some of the smallest points on the motherboard that I have ever soldered. Different versions of the 360 worked better but most worked even if it took a minute or so before the glitched worked and booted into custom firmware. Mine worked really well and booted first try almost every time. I was very proud to successfully install it and watch my 360 boot into fsd a custom OS that allowed me to play all my games from a HDD.