sorry.. i am not here often and I dont like the ubuntu much but anyway, i have used the toothpick method.
1) download the image
2) burn to usb key ( i have used sd card wuth adapter)
3) put the key into white usb slot
4) there is a button inside AV conector press and hold the button
5) power on device and wait few seconds, x96 logo will appear, keep holding the button, logo blinks once or twice and you will realize that initial animation did not start
6) release the button
7) wait armbian to boot