Issue with my Makerdiary Nrf52840 dongle : Not able to change the UF2 firmware

[ylg2935]

Hello ,
I just bought a GeeekPi nRF52840 Micro Dev Kit USB Dongle on Amazon
i'm following the guidelines indicated for the dongle ( https://wiki.makerdiary.com/nrf52840-mdk-usb-dongle/)
pressing the button, I can do a Drag/Drop operation on Windows and Linux and put the new firmware, but on both, the new Firwmare file that I put (nrf802154_sniffer_v0.7.2.uf2) is never saved (the new FW is lost after reboot, I'm retrieving the old one).
I have successed to download an open bootloader (the traces is below) but still the same result, I'm not able to put the firmware with the 802.15.4 analyzer...
Could you please help me ?
My goal is to do a 802.15.4 analyzer with this nRF52840 dongle.
Do you know how I can flash the nrf802154_sniffer_v0.7.2.uf2 using adafruit-nrfutil ? there are not providing the full package (I mean the uf2.zip file).

_C:\nrf52840_mdk_usb_dongle_open_bootloader_v1.2.0>adafruit-nrfutil --verbose dfu serial --package nrf52840_mdk_usb_dongle_open_bootloader_v1.2.0.uf2.zip -p com3
Upgrading target on com3 with DFU package C:\nrf52840_mdk_usb_dongle_open_bootloader_v1.2.0\nrf52840_mdk_usb_dongle_open_bootloader_v1.2.0.uf2.zip. Flow control is disabled, Dual bank, Touch disabled
Opened serial port com3
Starting DFU upgrade of type 2, SoftDevice size: 0, bootloader size: 34544, application size: 0
Sending DFU start packet
Sending DFU init packet
Sending firmware file
########################################
############################
Activating new firmware

DFU upgrade took 29.97208333015442s
Device programmed._

Regards,

Yvon LG

[raenye]

What is the current version of your bootloader?