Trying to setup DFU on PCA10056 to look like PCA10059

I have a PCA10056 (nrf52840 DK) and a couple PCA10059's (nrf52840 Dongle).

I'm trying to get the DK to have the same/similar DFU as the dongles.

My development machine is a linux system running ubuntu 18.04 LTS

What I did, using the nRF5_SDK_for_Thread_and_Zigbee_2.0.0_29775ac SDK:

USB cable plugged into J-Link USB port (J2):

cd examples/dfu/open_bootloader/pca10056_usb_debug/armgcc
make
make erase
make flash_mbr
make flash

LED2 is now pulsing on and off, indicating that its in DFU mode.

Move USB cable to the nRF USB connector:

cd ../../../../peripheral/blinky/pca10056/mbr/armgcc/blinky/pca10056/mbr/armgcc/
make
nrfutil pkg generate --debug-mode --hw-version 52 --sd-req 0x00 --application _build/nrf52840_xxaa.hex dfu.zip
nrfutil dfu usb-serial -pkg dfu.zip -p /dev/ttyUSB0 -b 115200

and the blinky program runs. If I hit reset it goes into the bootloader, but if I power cyclce it also goes into the bootloader and doesn't run blinky.

If I build blinky for the PCA10059 and flash using the same commands as above, then it runs blinky at poweron and at reset it runs the DFU.

What else do I need to do to make the DK behave like the Dongle? I know that the Dongle has the reset line hooked upto some GPIO pins, but I thought that this was just for the DFU trigger library?

I'm planning on use the 52840 for a zigbee application and do not need the soft device.