As suggested I reset router to factory default before flashing, then flashed using this file: factory-to-ddwrt.bin
Everything seemed gone ok but on the after the following reboot...it was not possibile to login.
So, according to various guides I performed a reset with the 30-30-30 rule twice.
Nothing to do, web interface appears but it dos not accept any password (and neither ask for a new password as should be if flashing was correct).
Alse leds behave "strange" flashing alternately.
EDIT: Now, after other 30-30-30 reset rhe web interface does NOR appera any more. Bricked?
So I think tftp is the last resource...
Can you point me to a safe guide about (with the right parameters for my router?). I feel a bit uneasy with cli.