Yeah iirc you could use a command line option to prohibit the steam update (step 3 in your process), but this feels very familiar. For reference I looked up the tool I mentioned

https://steamcommunity.com/app/353370/discussions/1/65161932...

https://steamcdn-a.akamaihd.net/steamcommunity/public/images...

But good to know that someone bothered to publish the written down instructions.

The official(ish) tool for restoring the firmware is, best I can tell, something a single employee put together in their spare time and tossed over the wall. The zip includes unrelated files and required DLLs aren't packaged. I recommend reading the entire thread before trying anything, though I tried to summarize correct instructions in post #99 of that thread.