Thank you. I thought that this kind of issue would be at least the title of a forum thread, rather than comments in general discussion. It took me many readings before believing that you really should flash it twice in a row. I think that a so "unexpected" procedure should be stated clearly in the installation guide.
By the way, after solving this issue by repeated flashing, I got into the boot-loop issue. I solved this by repeated flashing. Then, after installing google maps the device bricked. I solved this by repeated flashing again. Now everything runs fine except for the "music over earphones way too loud" issue that I've not been able to flash yet.
Sorry, but it points to nothing