I've put on the stock dfu/bootloader_secure on the nrf52 DK.
I've then create a distribution ZIP and upload a blinky app to the DK. That worked fine.
Then I compiled experimental_ble_buttonless_dfu, made a ZIP and uploaded it to the DK.
Looking at the RTT output, it seem that it is reseting it self over and over
UPDATE
This patch I made fixed the issues.
SDK12.2, arm,gcc