That's pretty much what I do when I need to go back more than a couple of firmware versions. Though I use
https://wiki.mobileread.com/wiki/Kobo_Firmware_Releases for the firmware links if I don't already have it downloaded. If I'm going back one or two firmware versions, I might not do a factory reset. It depends on the recent changes.
And the last step is no longer needed. But, I don't remember exactly which firmware version fixed the problem.