Xbox Series X Sync button/synced controller stopped. Sync button must work as I am able to...

Sync the Controller:
To sync a wireless controller with your Xbox, follow these steps:

Press the Xbox button on the controller to turn it on.
Press and hold the small sync button on the front of the Xbox Series X console (located near the USB port).
While holding the sync button on the console, press and hold the sync button on the controller (located on the top near the Xbox button).
Release both sync buttons when the controller's Xbox button starts flashing. The controller should now be synced with the console.

If you can use your controller while connected through USB, that means that the wireless connection between your controller and your Xbox is working. Even when connected through USB, the communication between both devices is done wirelessly, with the controller only using power from the USB cable, not data. The controller is paired to your console when connected through USB, so the issue lies on your controller.

Check if the batteries inside of your controller are installed with the correct polarity. If they are, try to replace them with Alkaline batteries and check again.

That's ok! We really hope that the update fixes the issue, that would be the best outcome! Let us know of anything new!

Have a great day, and if you have any other questions, make sure to contact us again!

Thank you for the suggestion. I connected the controller to my PC and did the following steps you mentioned. With a USB C cord I was able to reconnect the controller and pair it to my log in. It wouldn't however stay connected when I unplugged it.

This was after a 3rd factory restore of all settings and games. I am really frustrated as it worked earlier in the day as normal and as mentioned in the post the "sync" button itself must work if I can get to the BIOS (hold with power/sync button until second beep) however, the power button doesn't blink or go into "syncing mode" for some odd reason.

Maybe the Bluetooth went out? There is no way to reset this. I did the Ultimate Game Pass deal ( 2 years financed) for $900 so I would hate to send in and not have a console for a few months while using up Game Pass months. I can play with a cord at least.

Good suggestion regarding the phone attempt. Yes, I was able to connect to Bluetooth on my phone with the app and PC as mentioned before so this rules out the controller.

I guess the only solution is repair unless an update somehow fixes this. It's just so bizarre how it just stopped working after 2 weeks out of the blue and well after a week of the last update. None of the solutions from the other forums have worked either.

Thanks again for all the suggestions! I will edit this post if this is solved soon or close if need to send in.