if you have a Pro 4k, you need the p212 dtb file, not the p200. Double check your version in the About setting in Android or use CPU-Z
Thanks for your sugestion, but I definitely need p200 because SoC in my box is s905.
Box boots from SD with any of the gxbb_p200 dtbs but only with gxbb_p200_1G_mxq_pro_4k.dtb it boots from NAND.
Unfortunately, as dmesg shows no i2s and sound
It did boot from NAND and sound was OK with some older gxbb_p200_1G_100M.dtb, so I suspect that new dtbs introduced a bug.