Of course you can use official way to update the firmware.
But also here the programm which allow to update firmware without internet connection.
Home Page: http://deus.lipkop.club/
Direct link to download
This software IS NOT OFFICIAL updater and is intended for use solely for informational purposes.
The author is not responsible for any damage (material, moral or other) caused to you or third parties resulting from the use of this software.
All the steps you are at your own risk!