You may have already found the solution, but it wasn't posted here.
I was having the exact same problem, trying all the same methods with no joy. Searched on the Klipsch site and found this nugget site:
https://www.klipsch.com/firmware?product=110026&serial=
Seems the RSB-11 firmware updates are very serial number specific, otherwise it will stop at step 6!
Identify your soundbar S/N, download the proper firmware, load onto a blank thumb drive, and follow the procedures. Worked well for me.