Bangle.js 2 stuck in bootloop

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  • Hello,

    My Bangle 2 is stuck in a bootloop since 3 days. I can charge it and it will start the display but then get stuck in this eternal bootloop, until the battery runs dry. I've tried pressing the button for long or short intervals at any time of the process, but it does nothing. Am I out of luck?
    Please see the photos of the loop attached.


    4 Attachments

    • 1.jpg
    • 2.jpg
    • 3.jpg
    • 4.jpg
  • So you see the 4th image with Bangle logo and then it restarts itself to first image? Does the progress bar in second image goes like this till the end even if you don't push/hold the button at all?

    It would work exactly like that if the button would be stuck and always pressed. So maybe it is stuck in pressed state.

    Because normally the progress bar would not show at all unless you are holding the button (it says "release BTN1 for DFU" because it thinks the button is pressed).

    Also holding the button prevents watchdog kicking (by design, to have a way to reboot when device is stuck) so the watchdog reboots the device after some time and it starts over.

  • Hi there, thanks for your reply.

    So you see the 4th image with Bangle logo and then it restarts itself
    to first image

    Yes, this is correct.

    Does the progress bar in second image goes like this till the end even
    if you don't push/hold the button at all?

    Yes, this is also correct.

    I also thought the button could be stuck, but it doesn't "feel" stuck and can be pressed normally without it feeling off in contrast to earlier, when the Bangle 2 still worked normally.

    So are you thinking the button might be "soft stuck", so that the board thinks that it's stuck when it actually isn't? And if so, what could I do about that?

  • If you drained the battery completely and it still happens I think it is not "soft" stuck but really stuck. Well, unless you built your own firmware which is reading wrong pin. Maybe some piece of metal got in the way inside making contact. Maybe trying to shake it off somehow could help.

    Not sure how it looks inside, whether it is possible to still feel clicking like it is working normally while something broke inside and is permanently pushed. @Gordon perhaps knows.

    Unfortunately in this state you can't even flash some other firmware to test as you can't enter DFU so you would need to use SWD pins on the back with some SWD debugger dongle to flash something else.

  • That's unfortunate. I did not build and/or upload any other than the officially released (non-beta) firmware to the watch, so this won't be the cause of the problem I think. I also already tried shaking and mangling the button a little, but it didn't do anything.
    Could you please tell me how I can best contact @Gordon ?

  • Was your Bangle in water recently? It seems like me and someone else have an issue where the MCU thinks the button is constantly pressed because of water intrusion.

  • Now that it you mention it, yes, it actually was. I did not mention it because I didn't think it was related, because the Bangle was in water several times before and it was fine. But maybe an hour before the problem began it was in water. The thread you've linked makes me think it could be the same problem. That's very unfortunate as there seems to be no universally working solution currently.

  • Place it in a bag of rice for a few days, maybe it will dry out and start working again

  • Mine actually dried out on its own over the course of a few hours while I was still wearing it. But just in case I ran down the battery and left it directly under an incandescent light for a few hours. It doesn't seem to be damaged, but I'm now going to take it off before going into the water again.

  • Great - glad yours is ok @user141569 - if the battery is running down quick when it's wet, definitely don't recharge it until you're sure it's dry again.

    But sorry @user147840 - this sounds a lot like water damage to me. Definitely try and put it somewhere warm for a few days (without charging it more) and you might be lucky and it'll sort itself out.

    I'd normally be back to you a lot quicker but I'm afraid I wasn't in the office at the end of last week.

  • I'm also glad mine is OK. Well, the battery did run down quickly while the watch was bootlooping, but that was probably because of the backlight being on and the CPU being active for several hours straight. Probably about 80% when it started and 30% when it ended a few hours later. Battery life has been normal ever since. So I'm guessing we have no short circuits anywhere.

    And don't worry, even with the slight delay, the customer service is probably still the best I've ever experienced.

  • Thanks for your reply and don't worry about not being quicker. As @user141569 said, you were still much faster than most other companies' customer service!
    I will wait until early next week and try again. But in the meantime I'm afraid I'm out of luck, because I already tried to charge the Bangle a few days ago before I went onto the forum and it still didn't work. :(
    Then I'll have to try to acquire a new one soon.

  • Well, the battery did run down quickly while the watch was bootlooping, but that was probably because of the backlight being on and the CPU being active for several hours straight.

    In a way that's probably the best thing that can happen - the battery gets run down more quickly, the Bangle gets warmer internally and dries itself out quicker :)

    But it's definitely worth giving it time - even if the Bangle comes back to life it doesn't mean it's 100% dry inside, so long term it's better to give it a good long time to dry out.

    I'll reply in http://forum.espruino.com/conversations/­378470/#comment16640058 in a second, but if you do end up having to replace the Bangle I'm very happy to offer a discount. I don't think I should lose money replacing a water-damaged Bangle when the docs say no swimming, but I also don't want to profit from your misfortune :)

  • In a way that's probably the best thing that can happen - the battery gets run down more quickly, the Bangle gets warmer internally and dries itself out quicker :)

    Is the heat from the CPU and backlight really that significant?

    But it's definitely worth giving it time - even if the Bangle comes back to life it doesn't mean it's 100% dry inside, so long term it's better to give it a good long time to dry out.

    I guess I shall heat lamp it more. It's just hard to be without my watch for that long.

    I'll reply in http://forum.espruino.com/conversations/­378470/#comment16640058 in a second, but if you do end up having to replace the Bangle I'm very happy to offer a discount. I don't think I should lose money replacing a water-damaged Bangle when the docs say no swimming, but I also don't want to profit from your misfortune :)

    Thanks for the offer. That sounds pretty fair to me. I'm going to keep my Bangle for now, but if it dies I'll let you know.

  • Is the heat from the CPU and backlight really that significant?

    It's not huge, but it's better than nothing. The backlight is the biggest power draw in the system so I think it raises the internal temperature by a few degrees

    And you don't really want it powered any longer than required anyway because if it's powered while wet you get more corrosion on the PCB.

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Bangle.js 2 stuck in bootloop

Posted by Avatar for user147840 @user147840

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