If you are having a problem where your wireless Xbox controller is not being detected by your console (the circular LED keeps blinking), despite changing batteries, this simple trick will help you out.
There's a small button on the top right corner of your controller above the right LB and LT buttons. You'll see the same kind of button on your console (below the memory card).
Your Xbox will simultaneously search for your controller whilst your controller searches for the Xbox. This should solve your problem.
Photo by Glenn Carstens-Peters on Unsplash