2 Parts to this reply: forgive me if I post in the wrong area. I'm putting it in this thread because Part 2 may have to do with the firmware images you uploaded.
Part 1: These may be device specific issues for me. Well they are. But I feel it still important to mention them. I tried Firefox, Chrome,and Safari browsers on a MacOS to install firmware. In all 3 browsers every tab will open in the Setting's menu. Click the arrow and the box sections drop down... with the exception of the Update Firmware subsection. On the Mac's browsers the drawer starts to drop down like all the other tabs, but stops and leaves 1/2 and inch of white area. I see a quick flash of the "Choose File" text right when I click the expand arrow, but then is disappears (perhaps the way the page formatting is designed?). I turned off Adblocker and other browser addons to see if that helped. it didn't. I tried tabbing around the screen to see if I still could get to Choose file or Update Firmware buttons even though I could not see them, but can't navigate even that way to either. Every other tab on the list works perfectly fine. I'll test on a few windows machines tomorrow. It may just be my bad luck, but if it's an issue with Mac or your coding on how the page is displayed, but either way I think you should know.
Part 2: Couldn't upgrade the firmware on the mac so I went to Android. Copied the image file over to an android phone. In the end, the browsers on 3 phones and 1 tablet ALL display the Update Firmware section just fine fine! OK. So I load the file and start the upgrade. After a minute or so I get a red dialogue box, "Firmware update failed". Try android device 2. Same thing. Both 3 and 4 also Fail.
I tried downloading a clean copy twice (in case the D/L got corrupted) and same issue on 2 of the devices "Firmware update failed." At that point I didn't bother with device 3 and 4.
Just passing on my experience.