Nrf52 DFU OTA doesn't work

Apologies if this is the wrong place for this!

I have an NRF52 Itsybitsy board but for the life of me cannot get Bluefruit Connect to update the firmware via Bluetooth LE Over The Air. I've searched extensively for this but no luck.

To reproduce;

  1. Upload one of the simple sketches to the device - choose the simplest that has bluetooth and the bledfu profile advertising. Reset so it's advertising.

  2. Install Bluefruit Connect

  3. Select to the board.

  4. Select Update.

  5. Choose one of the examples to upload, or your own firmware.

I've tried multiple variations of this with multiple firmwares. I typically get 'OPERATION FAILED'. The board loses its application and when it resets, it's in a bare state; so I think the DFU has started but at some point failed. I don't know how this is possible as the bootloader should confirm the checksum of the uploaded application before copying it to the main application space.

Does anyone have any ideas? Is Bluefruit Connect actually compatible with the NRF52 boards?

Thanks! Nick