Stuck on firmware update screen (Failed to update firmware)

Hi, sorry you've hit this. Did you try the instructions on https://www.espruino.com/Bangle.js2#firm­ware-updates ?

Note: It has been reported that some users with modern iPhones find that the NRF Toolbox app disconnects from the Bangle after performing only part of the update process. If this happens to you, you'll have to manually click to start the update multiple times (it will start from where it left off) in order to complete the update.

So you just have to keep retrying the firmware update from the iPhone. I know it's frustrating but it should work fine (or if you have an older iOS or any Android device it should 'just work'). I am working on a better solution for this.