And here's the noob again, asking for help!
I updated my Kindle Touch to 5.3.7 (just because I wanted to check if komic works there...)!
Everything is gone, and I knew it.
I'm setting the kindle again, starting with the usbnetwork.
Usbnetwork works fine over USB, logging in with every possible password.
On the other hand, I can't login in WiFi mode.
It seems the password isn't correct: I changed it one year ago when first installing usbnet and I do remember it!
The kindletool doesn't provide a correct password (yep, it is no longer the stock one!)
Any clue?
How I managed to change my root password simply updating the kindle?