By tye way, you can go directly from 1.16 to 1.15.
Just rename the file to 'update'. Pull plug, finger on power button on viark and plug in. Remove finger when you see 'USB'.
Made it! Exactly as you suggested, dog-man.
Went back directly from 1.16 to 1.15 WITHOUT losing nothing.
The update process began just few seconds after powering up, and when the box rebooted V1.15 was installed.
It retained channel list, configuration, FS and SP1. And, last but not least, autobiss is back! Tried now with tennis feeds.
So, no need to install the original firmware.
Now, every time the box boots up, it detects V1.16 for download..... no problem, V1.15 is OK.
Thank you so much to everyone.