Can I close the browser and restart the process without bricking the watch?
Yes, it's designed such that if the update doesn't complete you can close and there are no problems.
Maybe just try again and see if that helps? Also if you were doing it via the app loaded in Gadgetbridge maybe try disconnecting from Gadgetbridge and doing it direct via Chrome in https://banglejs.com/apps
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.
Sorry it's not worked, however:
Yes, it's designed such that if the update doesn't complete you can close and there are no problems.
Maybe just try again and see if that helps? Also if you were doing it via the app loaded in Gadgetbridge maybe try disconnecting from Gadgetbridge and doing it direct via Chrome in https://banglejs.com/apps