Seeing that no one answer the question I posted on bootloader section, I decide to post the same question on all the sections about Nano PI M2 with Samsung S5P4418.
With ALL images availables (Friendlycore, Frienflywrt, Android and Ubuntu) the board don't boot: stops during uboot with the following message (taken from the UART console):

BL1 by Nexell V1.0.0-gd551e13 [Built on 2018-01-25 16:58:29]

Memory Initialize (0) Done.

Loading from sdmmc...
Image Loading Done!
Launch to 0xB0FE0400

U-Boot 2016.01-00041-ga7bea11237 (Nov 08 2019 - 16:56:31 +0800)

Model: FriendlyElec boards based on Nexell s5p4418
Board: s5p4418-X
DRAM: 1020 MiB
Panel: N/A (-1)
HDMI: display.0, preset 0 (1280 * 720)
HDMI: phy ready...
LCD: [HDMI] dp.0.1 1280x720 32bpp FB:0x77000000
In: serial
Out: serial
Err: serial

Hit any key to stop autoboot: 0
6165728 bytes read in 430 ms (13.7 MiB/s)
5880768 bytes read in 400 ms (14 MiB/s)
** File not found s5p4418-nanopi2-rev05.dtb **
libfdt fdt_check_header(): FDT_ERR_BADMAGIC
Kernel image @ 0x71080000 [ 0x000000 - 0x5e14e0 ]
ERROR: Did not find a cmdline Flattened Device Tree
Could not find a valid device tree