I had this problem a couple of weeks ago and my xbox has sat dead until last night. Nothing would work i tried everything and i have experience in being pc tablet phone laptop repairs for nearly 20 years. However. I found that my xbox didnt turn on as a result of a failed update, apparently my xbox power cycled through it which must of been when i was cleaning found this by debugging error log. If your xbox wont turn on and the power brick lights up orange to white and the xbox immediately shuts down on startup heres what to do. Unplug every lead out of the back of the console. Unplug the power brick lead from the wall then the power brick. Leave it for 2 hours or so. Plug it all back in. Try the controller, it should power up and try to connect to the xbox to turn it on but wont. While the controller is on double press eject. The console should spring back into life and connect to the controller. Job done. Hope this helps a vast amount of you that think you have a bricked xbox.