Secure bootloader doesn't start

[Anton K.]

Hi all. I try to implement ble dfu bootloader project via getting start from  SDK/examples/dfu/secure_bootloader/pca10056_ble_debug project. 

Using:

OS: Linux

Compiler: armgcc (toolchain gcc-arm-none-eabi-7-2018-q2-update), eclipse

Softdevice: s140_nrf52_6.1.1_softdevice

SDK: nRF5_SDK_15.3.0_59ac345

Hard: PCA10056 DK

I just successfully compile exist project and flash softdevice, then bootloader. I can't see any DfuTaarg on nRF Connect Mobile app. I haven't any errors messages, any warnings.
After flashing precompiled .hex to board. If seems work with BLE advertising of DfuTarg. What should I do?
Thanks for attention.

[Anton K.]

Also can't see any log information on RTT logger, he is enable, but where application after flashing I don't know. Trying to hard debug, but at first time after start pc seems at 0xfffffffe addr. I use Eclipse, so about hard debugging is hard for me say something good.