It might be a display issue. Check your HDMI connection. Try switching cables or ports on your TV. If the Xbox light is on in the front of the console, it won't start up unless it detects a working display.
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Check out the [https://www.ifixit.com/Wiki/Xbox_One_Won%27t_Turn_On|Xbox One Won’t Turn On] wiki for a more detailed list of causes and solutions for this problem.
It might be a display issue. Check your HDMI connection. Try switching cables or ports on your TV. If the Xbox light is on in the front of the console, it won't start up unless it detects a working display.