Today I had an Xbox One X come through that showed no signs of life. The power supply tested fine so I dug deeper and found the the 12v power rail was short to ground. Investigation lead me to the GFX Core and the mosfets on that 12v line. I found one of the fets short to ground and replaced this component which relieved the short and allowed the console to boot. It is a very common issue with the One S but not so much the One X. I had to harvest the replacement part from a faulty donor board. Here are a few pics of the faulty fet. They are a nightmare to replace as there is a resin applied to the edges which has to be carefully removed by scraping off with a shark edge and not damaging any part of the board or traces radiating from the component.