Hi there,
Another SSA3021 sucessfully crossflashed here.
I used the instruction recap from @maximevince at post #1223 from this thread.
Thanks to all the contributors!
Small thing:
The backup require to mount the USB device in RW mode:
$ mount -o remount,rw /usr/bin/siglent/usr/mass_storage/U-disk0
Also, this is not super n00b friendly as a procedure, maybe it's better that way.
In all cases, if you never used vi to edit a file, this is not a procedure you should attempt (yet).