MaskRom Upgrade Mode failed

Maverick_by

MaskRom Upgrade Mode failed

Hello,
im trying nake MaskRom Upgrade Mode for Linux for mb-jm3-rk3568 motherboard with core board Core-3568
I use this link 3. MaskRom mode
https://wiki.t-firefly.com/en/Core-3568J/04-maskrom_mode.html
And i used 4.3.2.1. The Method from Firefly
https://wiki.t-firefly.com/en/Co ... re_with_flash.html#

First time i successfully made firmware update using The Method from Firefly and my system loaded Ubuntu 18.04

But when i wanted update firmware using RKDevTool with RK356x_NorFlash2eMMC-Loader_xxx.img file again it ALWAYS stuck on upgrade:

Download Boot Fail

can you help me with that ?