What is the image trying ?
Armbian_5.71_Aml-s9xxx_Ubuntu_bionic_default_4.20.2_20190118.img.xz
What dtb ? How do you set up a dtb ?
I remember not having to install a DTB because everything worked out of the box.
What is the exact version of the image installed on the eMMC ?
I believe it was the 5.34 server image.
What media are you trying to use (sd or USB) ?
I have tried both but it is either not booting at all or booting from MMC and oopsing..