I did it exactly as you write, Greg. But it doesn't want to update
Will try to download the file one more time. There is the only iso file on my stick.
I guess there is no update for rest of world - where russia is included. And I can not find any link for the latest possible software...
European package does not fit my bike
update:
Finally I found the solution. There are different p/n of Boom Box. Mine is ...232 and it is not a CVO premium unfortunately (I don't know why FLHTKSE is equipped with it, but still it is). I downloaded a simple Premium Radio file for ROW and updated my bike.
We checked together with my dealership other bikes and there were Boom Boxes with part numbers ...231, 231A, 232 (for European market and for rest of world)
I hope this information will be helpful for someone else