nRF52840 Dongle restore bootloader

[piers]

It appears that the DFU bootloader has been overwritten/damaged on nRF52840 Dongle as it no longer resets (the red flashing led does not show) when I hit the RESET button. This happened when I was trying to use the Power Profiler app from the nRF Connect App (v3.6.1) on MacOS10.15.7 and after the point where it asks to reprogram the Dongle it got into this state. I had previously successfully tried the Bluetooth Low Energy app. I also tried the RSSI app but it wouldn't work (it tried to reprogram the dongle but failed to work but it did reset afterwards).

How can I reload the original DFU bootloader or restore it to its original state? I no longer see the device in /dev/ so unclear how to proceed? Do I need to a buy a 'DK' board to fix this or can it be done just with my laptop?

Thanks,

Piers

[Simonr]

Hi Piers

I'm sorry to hear that. I assume you refer to the power profiler app in nRFConnect? This app is not intended for the Dongle at all, but rather our Power Profiler Kit 1 and Power Profiler Kit 2. Flashing the Power Profiler firmware onto the Dongle mightindeed have erased the bootloader. It should still be possible to flash the debugger back onto it, but you will need a DK or J-Link debugger to do so I'm afraid.

It should not be necessary to handle it with any excessive care in regard of ESD, as it is rated to ESD HBM class 2 according to the nRF52840 PS.

Best regards,

Simon