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Firmware Recovery

If the watch firmware is not working (crash loop, frozen screen, etc.), normal BLE firmware updates won't work. You can recover using the built-in MCUboot bootloader.

tip

For a full guide on initial setup and firmware updates, see the WatchDK Quick Start.

Recovery Without a Debugger​

  1. Connect USB: Make sure the watch is connected to your computer via USB-C.
  2. Enter the bootloader: Hold down the two right buttons simultaneously for approximately 20 seconds. The display will go blank. This means MCUboot is active and waiting for a firmware image over USB.
  3. Flash via the web updater: Go to zswatch.dev/update and perform a firmware update over USB.

Recovery With a Debugger (SWD)​

If you have a debugger (J-Link or nRF54L15 DK) connected via the 10-pin SWD cable:

Follow the steps in Firmware Updates, using the SWD method.

In recovery scenarios, prefer a full erase and re-flash of the application core.