For anyone who might need it,
I tried this fix, and while it DID update the firmware properly (and prevent the software UI from repeatedly prompting me to update), my mouse did not automatically work like the instructions claimed.
I was able to get it back in working order though!
I discovered that if I changed the default profile in the UI from Profile 1 to Profile 2 it worked again!
The UI has an option to reset a profile in the top right corner menu. I reset Profile 1, and it was working again properly!
So if you're having trouble getting the methods above to work, try that method.
(i also had to download winrar to get the download to work, so if you're having trouble with that too, that's probably what you need to do!)