Xbox one controller blinks even though I tried to sync it

Is this a genuine xbox one controller?

How long have you had it?

How long has it been blinking? Meaning when was the last time it worked correctly?

Was this a new controller that came with the xbox one or purchased separately?

Try removing the batteries from the controller. While they are out in plug the xbox one taking out the power cord. Wait 2 minutes. Put the batteries on the controller first put the battery back back on then plug the xbox one back in and plug in a USB to
to controller and plug the other end in the xbox one wait until it works then unplug the USB press and hold the xbox button on the controller to get the menu that says turn off xbox or controller...pick one after it does turn it on using the xbox button on
the controller to see if it works.

I know this may sound obvious, but are you certain the batteries are charged? I would check this first, as it's the simplest solution.

Hi Box,

Make sure your console is plugged directly into a wall outlet also. Have had instances where a power strip has prevented controllers from syncing, as the console is not getting enough power.

Thanks,

Brad

Try performing a hard reset EXACTLY like this. Hold the power button on the console for 8 seconds or until the power shuts down completely.
Unplug the power cord from the back of the console for 5 minutes.
Plug the power cord back in and restart the console.

If a powercycle doesn't work then do a factory reset on the console. There's an option to keep installed games and apps and your saves are safe on the Cloud. The reset will force the controller to connect again.