Re: why can I not get my HTC one to turn on. It shut off by itself
Welcome to Android Central! M7, M8, or M9? Have you tried pressing and holding the Power button for 10-15 seconds? If that doesn't work, the battery may have failed (or worse yet, the motherboard). You'd need to bring it to a repair shop (unless it's an M9, or possibly an M8, in which case it should still be under warranty).