This worked on my X920.
I did have a hiccup the first try. It would get to 99% and then say something like "...Incorrect SD Card..." I quick reformatted my 16 GB Kingston card with FAT32, used a different computer to copy the same files with 7-Zip, and the second try was flawless except I can't upgrade my bluetooth firmware. My bluetooth firmware is at 3.11. The option is greyed out. Another difference was that after the update, I could not select different languages. US English was already selected and the rest were greyed out.
This was my first update on my unit.
Any ideas?