Chosen Solution
I bought an Xbox one from a guy and when I got home it wouldn’t power up at all so I took it apart because the guy didn’t take care it and it was dirty. So once I put it back together, it came back on but only when using a controller. The power button on the console won’t power it up. What could be the issue?
Either the RF board or the soft-button flex cable that attaches to the RF board is faulty. The latter is more likely. Remove the front plate, and attempt to manually power it on by shorting the bottom two pins (1 and 2) on J3 (the ZIF socket where the front soft button flex goes on) to bypass the soft-button flex cable. If that works, you need a new soft button flex cable. If it still doesn’t work, disassemble the whole unit and look for a bare header under the optical drive that’s clearly labelled POWER - you can short those two points to also attempt a manual power on. If that works, you probably need a whole new RF board (and possible a flex cable too). Both are relatively inexpensive to replace.
