PCA10056 rev 3.0.3 (2026.7) - J-Link OB nRF5340 stuck in bootloader, firmware update always fails

RE: PCA10056 rev 3.0.3 (2026.7) - J-Link OB nRF5340 stuck in bootloader, firmware update always fails

Menon — Wed, 08 Apr 2026 13:27:50 GMT

Hello,

If neither of those options updates the debug firmware, then I do not think there is a way to recover the device.

[quote user="AMC0"]I believe this is a factory defect. My distributor (Mouser) is already sending a replacement unit. Is there anything else I can try, or can you confirm this board is defective?[/quote]

It is good to hear that you are receiving a replacement. Usually, this does not happen, and I am not entirely sure what might have caused the issue in this case.

Please let me know once you receive the new DK and confirm that everything is working as expected.

Kind Regards,

Abhijith

RE: PCA10056 rev 3.0.3 (2026.7) - J-Link OB nRF5340 stuck in bootloader, firmware update always fails

AMC0 — Wed, 08 Apr 2026 12:59:56 GMT

Hi Abhijith,

Both suggestions failed:

1) nrfutil device x-update-debug-probe-firmware --serial-number 1050245467
Result: "Emulator error: No emulator with connection info 'Usb(JLinkSerialNumber(1050245467))' was found"

2) JLinkExe → connect after firmware update failure:
Result: The firmware update fails first ("Communication timed out, Emulator did not re-enumerate"), then the connect command returns "J-Link connection not established yet but required for command. Connecting to J-Link via USB...FAILED: Cannot connect to J-Link."

The J-Link OB is completely unreachable after every firmware update attempt. The firmware data is always sent successfully (1019904 bytes OK), the emulator detaches, but it never re-enumerates on USB. This happens on both macOS (Apple Silicon) and Windows 10 with J-Link V9.24a and V9.32.

I believe this is a factory defect. My distributor (Mouser) is already sending a replacement unit. Is there anything else I can try, or can you confirm this board is defective?

Thank you,
François

RE: PCA10056 rev 3.0.3 (2026.7) - J-Link OB nRF5340 stuck in bootloader, firmware update always fails

Menon — Wed, 08 Apr 2026 10:29:45 GMT

Hello,

Could you please try running the command nrfutil device x-update-debug-probe-firmware? This updates the firmware on the SEGGER J-Link debug probe present on the DK. Please check whether this resolves the issue.

If that does not help, please open J-Link Commander and run the connect command, as this may also recover the device.

Kind Regards,

Abhijith