A few weeks ago, while working, my 2015 12" retina macbook suddenly shutdown. It was plugged in, and was almost warm, not even hot. I tried holding power button, resetting SMC, trying different key combinations etc., but it was dead. Researched the situation as best as I can, but all I can find were a couple of tips that didn't help. I waited a couple of hours, tried some more key combinations, and it was still dead. Than I stumbled upon a video from Louis Rossmann. According to Rossmann "the U4700 USB-C communication controller on the Logic Board fails, resulting in a low input voltage on the PP3V3R3V0_A0N (Always On) rail. The result is a computer that won’t charge or power on." Just like in the video, when plugged in, the bottom of my Macbook gets warmer (probably from the short). That's when I lost all hope, my 3 years old Macbook, with its 1.5 years old motherboard (it was replaced when graphics failed within ~18 months) was a brick. Apple quoted me ~$500 to replace the motherboard, but previous two didn't last more than 1.5 years and I don't want to spend almost half of its retail for something probably won't last a couple of years. Anyway, it took me all day to figure it out, so if your 12" Macbook 2015 A1534 suddenly shuts down and won't turn back on, and its bottom gets warm when plugged, it's probably U4700 IC failure.