Nrf54l15 Seeed no longer shows up in windows via USB

[stearnsbq]

Hi Everyone,

I have recently started dabbling into embedded projects with first working on an adapter for a i2c based controller and adding bluetooth support using one of the seeed nrf54l15 boards to get started.

I modified the hog.c/h file from the bluetooth sample and now I can no longer connect to the device or it shows up in windows at all.

The bluetooth connection still works and Im able to connect to do what I could with the code I had so far.

Ive tried following these older un-bricking threads and no luck, I assume mainly because the only ones ive found on this forum are for the arduino boards.

How to unbrick a dead XIAO using ST-LINK and OpenOCD

Hi, Using an inexpensive Chinese ST-LINK and OpenOCD for Windows, I was able to repair the XIAO bootloader. Here is a summary of the procedure. I hope it will be helpful. Reference: Wiring and Test | Programming Microcontrollers using OpenOCD on a Raspberry Pi | Adafruit Learning System Download OpenOCD for Windows from https://gnutoolchains.com/arm-eabi/openocd/ and extract it to C:/OpenOCD. Copy the file C:/OpenOCD/share/openocd/script/target/at91samdXX.cfg and rename it XIAO_at91samdX…

XIAO BLE (Sense) bootloader bricked, how to restore it?

I was able to unbrick my XIAO BLE sense with OpenOCD using a raspberry pi as SWD debugger / programmer. I just set up a fresh Raspberry PI OS on a Raspberry PI Zero W, and installed openocd (“sudo apt install openocd”), wired the XIAO BLE sense to the Raspberry PI (see below), and executed the following command: sudo openocd -f interface/raspberrypi-native.cfg -c “transport select swd” -f target/nrf52.cfg -c init -c “reset init” -c halt -c “nrf5 mass_erase” -c “program Seeed_XIAO_nRF52840_Sens…

I tried running this command

C:\OpenOCD-20260121-0.12.0\bin\openocd.exe -f interface/stlink.cfg -c “transport select swd” -f target/nordic/nrf54l.cfg -c init -c “reset init” -c halt -c “nrf5 mass_erase” -c “program firmware.hex verify” -c reset -c exit\

Warn : Transport “swd” was already selected
Info : STLINK V2J37S7 (API v2) VID:PID 0483:3748
Info : Target voltage: 3.238477
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : clock speed 950 kHz
Info : SWD DPIDR 0x6ba02477
Error: [nrf54l.cpu] Examination failed
Warn : target nrf54l.cpu examination failed
Error: [nrf54l.aux] Examination failed
Warn : target nrf54l.aux examination failed
Info : [nrf54l.cpu] starting gdb server on 3333
Info : Listening on port 3333 for gdb connections
Info : [nrf54l.aux] gdb port disabled
Info : [nrf54l.cpu] AP write error, reset will not halt

I noticed the factory_reset.bat detects my stlink but I get this error:

.\factory_reset.bat
Reusing existing virtual environment.
Activating virtual environment…
Dependencies are already installed.
2026-02-16 18:54:45,031 [INFO] Auto-selected single probe: 000000000000000000000001 (STM32 STLink)
2026-02-16 18:54:45,031 [INFO] Attempting mass erase (will unlock if protected)…
0001053 E Error reading AP#0 IDR: STLink error (5): No device connected [discovery]
0001056 E Error reading AP#1 IDR: STLink error (5): No device connected [discovery]
0001060 C Error: 0 [main]
2026-02-16 18:54:46,210 [WARNING] Mass erase failed, try standard erase…
0001038 E Error reading AP#0 IDR: STLink error (5): No device connected [discovery]
0001041 E Error reading AP#1 IDR: STLink error (5): No device connected [discovery]
0001048 C Error: 0 [main]
2026-02-16 18:54:47,375 [ERROR] Standard erase after mass failure also failed.

[PJ_Glasso]

Hi there,

So I looks to be soft_bricked, Those links are for the nRF52840 Parts, Try this one,

Seeed Studio XIAO nRF54L15(Sense) | Seeed Studio Wiki

Restore factory settings

For XIAO nRF54L15 boards, a factory reset script is provided to recover the board from a bad state (e.g., when it’s can not upload due to the internal NVM write protection). This script will perform a mass erase of the flash and program a factory firmware.

Factory Reset

Location The scripts are located in the scripts/factory_reset/ directory. Usage The script will automatically create and manage a local Python virtual environment to install the necessary tools, so it can be run out-of-the-box.

Window

• For Windows: Navigate to the scripts/factory_reset directory and run:

.\factory_reset.bat

HTH

GL PJ

FYI, So without a JLink (connected to SWD) it may take a few cracks at it, just know that.

[stearnsbq]

Hi, I just have a st-link device and put some probes on the pads on the back of the XIAO, however the reset script hits that error like in the bottom part of my post. If I need a jlink device then I could try that once one of those comes in.

[Toastee0]

You should be able to repair it simply with pyocd and the mass erase command twice.
It always looks like it fails the first time and then it works the second for me.

Connected just via usb..

No need for using the bottom pads.

(Which can also work, it’s just harder)

[stearnsbq]

I’ve tried this already unfortunately. the issue I’m having is the USB stack in general on my device is corrupted or got overwritten so it won’t even show up in windows even as a unknown device.

[Toastee0]

So there’s two mcus on the Xiao nrf54L15, the Nordic soc, and a seperate samd chip with cmsis-dap firmware on it. The secondary MCU provides the usb host interface to the usb C connector.

You can access that samd MCU from the debug pads on the bottom, using SWD debugging.

Sounds like something might be wrong with the debug MCU or it’s firmware?

[stearnsbq]

probably, I’m not sure where I could get a firmware file for flashing that, the firmware.hex given as part of the reset script is for the nrf side. I think the cmsis-dap firmware on the samd11 got screwed up.