Hi
Workaround by installing 3.197 from https://community.volumio.com/t/community-based-change-log-for-volumio-3/53248
a. the mention “alpha or beta” made me uncertain about the quality of the status/quality of the image. Was it the same as the one installed through the plugin ?
b. Odroid-specific thread/link is a very good example
For Volumio 2.xx, something simiar existed. (i used to be able to re-download 2.698 for the Allo Kali & Piano Dual Mono issue)
c. If the update plugin stores a few releases, that would be very good if it could be possible to easily go back through the plugin (i haven’t tried to see if possible right now).
It would be have been easier than tracking down a post, redownload, flash…you know the drill! 
In any case, thanks for the pointer, the answers!
Have a nice day