A few days ago I started a cycling activity on my 830 and after a couple of minutes the screen turned white and showed what I think was a gps firmware update. The screen then turned back on the cycling activity but the device was very slow and unresponsive. I waited a couple of minutes and I tried turning it off, which took a lot. Now the device is stuck in a reboot loop. Every time I turn it on the Garmin logo shows and it beeps, after 2 seconds the backlight turns off but the Garmin logo remains, and after two more seconds the logo disappears and then it repeats the process with the boot and the beep endlessly. The only way to stop it is to press the power button for 15 or so seconds. I already tried every possible button combination that I found on this forum. I tried performing a master reset holding the power, lap, and start button in every possible combination and timing but the behaviour doesn't change, it keeps rebooting. I tried putting the device in mass storage mode holding the lap button while plugging the cable and connecting to a computer and it doesn't work. The only different behavior is that only the Garmin logo appears and disappears, but I don't hear the boot beep, and on the pc I hear the classic connection sound and after a few seconds the disconnection sound when the device reboots. I tried both keeping the lap button pressed and releasing it in different moments during the process. Nothing works. As soon as I release the lap button the endless reboots goes on but this time the beeping restarts. I tried letting it keep rebooting until the battery ran dry. I was in a situation where when I pressed the power button the Garmin logo showed and disappeared after less than half a second without the beep. After I connected it to a power source the endless reboot restarted. Any advice on what I should try next? I'm not afraid to tear it apart if I have to. Warranty is expired a few years ago.