Xbox One Controller light blinking non-stop, can't sync, after unsuccessful update

Try the following:

Make sure there are no batteries in it Plug the controller in via USB Hold down the controller's Xbox and menu buttons for 5-10 seconds Step two is critical to your success you must hold both button down at the same time (Hold down the controller's
Xbox and menu buttons for 5-10 seconds) Controller should turn on.

If you get the controller to turn on it may still need the firmware update since you are on PC here is the instructions:

Update via PC

Update your controller on a Windows 10 PC by using the Xbox Accessories app:

1. Get the app from Microsoft Windows 10 by searching for "Xbox Accessories."
2. Launch the Xbox Accessories app.
3. Connect your Xbox One Wireless Controller by using a USB cable or the Xbox Wireless Adapter for Windows.
   
   Note You'll be prompted to update to Windows 10 Anniversary Edition if you haven't yet done so.
   
4. When the controller is connected, you'll see the message Update Required if an update is mandatory. Install the update.
   
   Note You can also go to Device Info to check for an update.
   

Notes

• The Xbox Accessories app is available only on Windows 10.
• Controllers that don't have a built-in 3.5-mm audio port must be updated using a USB connection and must have the Windows 10 TH2 Update (or later).
  
• Updating the controller over Bluetooth is not supported.
• Bluetooth requires a PC running the Windows 10 Anniversary Update. See
  Windows Update: FAQ to learn how to get the latest Windows update.

Hi, thanks for sharing.

Have you tried to power cycle your console?, this may help in most cases. I'll leave the link here so you can check in a more detailed way.

https://support.xbox.com/en-US/xbox-one/console/power-cycle-console

Well, tried turning off the computer and back on, but nothing. I even tried using the controller in another computer to see if it would work, but it didn't.

Tried that, but it never syncs and never stops blinking the logo light, I think the update corrupted whatever software the controller has for syncing. The only solution that comes to my mind would be some kind of software to reset the controller's configuration
to its factory default settings, but there doesn't seem to be anything like this for download and from what I've read, the controller itself doesn't have such a switch, as one would expect with some other types of electronics.

Have you tried plugging the controller in via cable with no battery pack? Just until it syncs then unplug the cable and put the battery pack back in. Hope this fixes your issue