Xbox One developer has revealed how to unlock some of that functionality for the development functionality built into the Xbox One by simply going into the Settings and pressing left bumper, right bumper, left trigger, and right trigger will enable what folks have dubbed the "devkit mode. However this alone does not actually turn the console into a developer kit. In addition, changing the settings in that menu is only intended for developers for Xbox One, and that alone does not turn the console into an actual development kit. And finally, Microsoft is strongly advising consumers against changing these settings as it could result in their Xbox One becoming unusable. Customers who have put their consoles into this developer setting can revert by restoring factory defaults under Settings / System, select Restore Factory Defaults. Read the full story here.
While Microsoft acknowledges that all Xbox One consoles will ultimately have the capacity to perform as a development unit, Microsoft is warning users from actually using it.