Orbi RBR50/RBS50 - Cannot downgrade firmware

Lots of users have manually installed the 2.3.5.30 (or 2.3.5.34) firmware on their RBR50/RBS50 systems using the web interface.  Did your procedure follow these steps:

• Write down the IP address of the Orbi router and satellites.
• Browse to the Netgear support site and download the firmware for RBR50 and RBS50:
  http://www.downloads.netgear.com/files/GDC/RBK50/RBR50-V2.3.5.30.zip 
  http://www.downloads.netgear.com/files/GDC/RBK50/RBS50-V2.3.5.30.zip 
• Extract the .img files from the zip files using whatever "unzipper" is on your system.
• Using the web browser, connect to each of the satellites, i.e. http://<ip of satellite>
  Log in with the administrative password
  Click on the menu item Firmware Update
  Browse to the location of the satellite .img file
• Then, browse to the router, http://<ip of router>
  Log in with the administrative password
  Navigate to the Advanced Tab->Administration->Firmware Update (last item under Administration)
• Click on the tab "Manual Update"
• Find the router .img file and do the update.

At this point, all of the Orbi's will have the chosen firmware on them.  You can perform a "factory reset" if you want to (or not).

WHERE in this process is it failing for you?