I had a similar problem with my I1Pro. Turns out I was using the wrong link on the firmware - d'oh! Somehow I ended up on the plain ol Inspire-1 page, not the I1Pro-Raw page (which has separate links for the Pro vs Raw). I was just typing in the dji URL and then going straight to the downloads section, so didn't notice that the Inspire-1 link was being offered first on both the Mac and Windows machines I was using (to pull my hair out).
If you've been through FW updates before, you may already be tuned in to the different pages, so this may not be your problem, but just wanted to offer it up.