This has been tested on linux, but it probably works on Windows too if you use git bash and are able to ssh into the pi
1. Connect to the banana pi via ethernet. You need to set a static IP like usual to be able to ssh
Go to network settings and set the static ip address settings like this
After setting it, unplug and plug back in ethernet
2. Enter this command
ssh ift@192.168.144.54 "echo 'weflydrones' | sudo -S dd if=/dev/mmcblk0 bs=4M" > debian_backup.img
3. Type password. Then wait for a long time. Generating the image takes a long time, probably an hour or more. The file created will be very large, over 50 GB