Thank you for the precise intructions. I followed them very closely, alas, no luck.
The attached firmware uploaded successfully and I was presented with the "Hold button to reload" message. So I pressed the button and kept pressing it. The boot screen came up with the "Storage ok" message, and I kept pressing it. But it was again stuck in that cycle. It never gets to the clock or the "=====" as you've mentioned. I've never seen those on the screen at any time.
So I decided to go ahead and open up the https://banglejs.com/apps link and connect to the watch while it was displaying the "Storage OK" screen. That works, and I can connect to the watch. I then went to "About" on the website on my phone and chose "Install default apps" (I chose "Remove all apps" first, which also went well). This worked, and it reinstalled all apps and I once again got the "Hold button to reload". Again, it got stuck at the "Storage OK" screen. I then reconnected through https://banglejs.com/apps on my phone again, and decided to try and upload the "Cutting Edge build" firmware as you mentioned through the "Firmware update" app. This took a while, but it got uploaded just fine and I again got the "Hold button to reload" message and it would load the clock, seemingly just fine. But when I pressed the button again for 10 seconds, I am right back in that loop where it gets stuck at "Storage OK", just like before. Nothing seems to have changed, unfortunately...
I've tried keeping it pressed for a minute, it just keeps cycling back to that "Storage ok" screen.
EDIT: Just noticed it still says "2v10.219" on the "Storage OK" screen, so I guess it didn't actually update the firmware although it uploaded something. The version chosen in the updater was "2v10.244".