Update bootloader

I use nRF52840-Preview-DK PCA10056 v0.9.3, SDK 14.1.0. I would like update bootloader, but i have any problems. I do these steps 1.eraseall 2.program softdevice 3.load bootloader 4.load application 5.load bootloader package zip file.

My problem is that, when I load bootloader package zip file it does not work.

Thanks in Advance, Hayk.