This is what I retrieved from USB to serial log:
Full log here.
Anyway TWRP still doesn’t load
Interestingly, with stock Android 6 ROM that comes preinstalled with Khadas VIM Pro, TWRP does load - holding POWER and pressing RESET and releasing it, still holding POWER until USB key starts being read.
@Gouwa, @terry, maybe uboot differs between what’s on GitHub and what’s where you build stock ROM from? Can you please check it?