1) I burnt Armbian_20.05.0_Arm-64_bionic_current_5.6.0-rc6_desktop_20200326.img on SD card. 2) In uEnv.txt I referred to meson-sm1-sei610-ethfix.dtb  3) Renamed u-boot.sd to u-boot.ext 4) I reset the box  I don't know if hdmi sound works as I use usb sound. Wifi works fine.