some people are having troubles with booting with Petitboot loader. In case you have troubles too, you need to disable Petitboot by running fw_setenv skip_spiboot true in the command line of Petitboot On modern kernels adding “video=HDMI-A-1:1920x1080M@60D” to boot /boot/armbianEnv.txt (extraargs=) should force HDMI to 1080p instead of the 4K native resolution.