You can use the standard activation procedure of the multi-download through the app “UpdateLocale”. Here is an excerpt from the description RDFTKV.
0.) To download an image, unpack, write image to media (SD or USB).
1.) With the Vim running Android, insert the prepared card (or USB flash) in to the Vim’s SD slot or use a USB card reader (or USB flash to USB).
Note: I like to use a card reader with activity LED, so I can see something is happening. The first boot can take a few minutes and the flashing LED is reassuring. 
2.) At Android/Settings/About Device/System/updates.
From the Update and Backup App, under the UpdateLocale section, click Select, select aml_autoscript.zip, click update.
Note: Leave “Wipe Data” and “Wipe Media” unchecked/unticked. To be clear, do not use those options
-The Vim will reboot, it will do so a couple of times.
P.S. I will be very grateful to those who will make a video on how to activate the multi-boot. It’s all very simple, but it is better “to see once than 100 times to read”.