Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

lcj — Sat, 24 Jan 2026 15:47:19 GMT

I have the new nrf5340DK and have been following this guide. Which shows this setup:

My setup looks like this:

Before attaching the ribbon I reboot the Thingy53 holding down SW2 and then releasing a few seconds after turning on I get this in the programmer:

So I know the Thingy is working. I see this in VS Code:

The refresh button shows this in the output:

[10:35:37] nrfutil-device device-info --serial-number XXXXXXXXXXXX --skip-overhead --json

[10:35:37] Success.

I plug in the 10-pin JTAG cable and connect the dk to the thingy and hit refresh in VS code I see this:

and the output console shows this:

[10:37:49] nrfutil-device device-info --serial-number XXXXXXXXXXXX --skip-overhead --json
[10:37:49] Error: One or more device info tasks failed:
 * XXXXXXXXXX: Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)).
   
   This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled (Generic)

The programmer now shows this:

When I try to flash it from VS Code I get this:

 *  Executing task: nRF Connect: Flash: hci_pwr_ctrl/build_53 (active) 

Flashing build_53 to Jan26-nrf5340dk
west flash -d /Users/XXXXXXX/XXXXXXX/hci_pwr_ctrl/build_53 --dev-id XXXXXXXXXX

-- west flash: rebuilding
[0/10] Performing build step for 'ipc_radio'
ninja: no work to do.
[1/10] Performing build step for 'hci_pwr_ctrl'
ninja: no work to do.
[8/9] cd /Users/XXXXXX/XXXXXX/hci_pwr_ctrl/build_53/_sysbuild && /opt/nordic/ncs/toolchains/5c0d382932/Cellar/cmake/3.21.0/bin/cmake -E true
WARNING: Specifying runner options for multiple domains is experimental.
If problems are experienced, please specify a single domain using '--domain <domain>'
-- west flash: using runner nrfutil
-- runners.nrfutil: reset after flashing requested
-- runners.nrfutil: Flashing file: /Users/XXXXXXXX/XXXXXXXX/hci_pwr_ctrl/build_53/merged_CPUNET.hex
Error: One or more batch tasks failed:
 * XXXXXXXXXX: Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)).
   
   This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled (Generic)

FATAL ERROR: command exited with status 1: nrfutil --json device x-execute-batch --batch-path /Users/XXX/XXX/hci_pwr_ctrl/build_53/generated_nrfutil_batch.json --serial-number XXXXXXXXXX

 *  The terminal process terminated with exit code: 1. 
 *  Terminal will be reused by tasks, press any key to close it.

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

Turbo J — Tue, 20 Jan 2026 17:29:46 GMT

Default firmware image may be locked.

Try west flash --recover or west flash --recover -r nrfjprog

Note that this will erase the bootloader from the device - it will be bricked until you can connect a debugger that supports Armv8-M. No idea if your DK does - it has the newer style debug chip which I am not familiar with.

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

lcj — Tue, 20 Jan 2026 17:14:22 GMT

I want to flash and debug the Thingy53 from VS Code with the nrfConnect for VS Code Add-In like I do with a Development Kit.

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

runsiv — Tue, 20 Jan 2026 13:18:45 GMT

Hi Leo

It seems to be a bit of a mix here. So let's clarify what the goal is

1. Can you show me an image of your setup?

2. Is the goal here to remove the bootloader on the thingy or maybe restore it?

Regards

Runar

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

lcj — Tue, 20 Jan 2026 13:09:58 GMT

I just ordered another nrf5340 DK but this is my nrf52840dk:

RE: Cannot Flash Thing53 using the debugger on a nrf52840DK with nrfConnect for Visual Studio Code

Turbo J — Tue, 20 Jan 2026 10:31:39 GMT

Not possible with some older DKs - they don't support the Cortex-M33 MCU cores:

This screenshot was taken with the NRF52840 DK clone from rigado.

Don't have a newer nordic nrf52840 DK here.