Try updating the firmware again via the app loader in a new browser tab.
Go back to web IDE tab, if you see some error message or strange output in the console window after a while copy and paste in a new comment here.
Cancel the update when you feel you've waited enough.
Reload the app loader and do a backup under the "More..." tab (maybe attach it to a comment here for possible debugging)
Mark all installed apps as favourites.
Do a factory reset of the Bangle either via the settings app, or by entering Bangle.factoryReset() in the console window of the web IDE when connected to the watch.
When the watch is finished resetting, connect to app loader and try updating the firmware again.
If updating worked, choose "Install favourite apps" under the "More..." tab on the app loader.
If the problem wasn't solved, restore the backup from step 5 to get all your stuff back.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
If you haven't already, I'd suggest:
Bangle.factoryReset()
in the console window of the web IDE when connected to the watch.