https://devzone.nordicsemi.com/questions/91169

espruino_1v86.90_nrf52832_full.hex         <-- Original working bootloader + sd + app
espruino_1v86.90_nrf52832_dfu.zip          <-- App DFU file
espruino_1v86.90_nrf52832_after_dfu.hex    <-- Memory dump after DFU
espruino_1v86.90_nrf52832_sml.zip          <-- Smaller App DFU file (same problem)