I didn't try to downgrade the firmware, it was I used the wrong image
I download some firmware looking for the right one, but it was ever the 001 variant
Finally I found this version 059K0Z2_RM-696 NDT GERMANY CYAN 16GB containing:
- D4A3D2AC_DFL61_HARMATTAN_40.2012.21-3_PR_LEGACY_009-OEM1-958_ARM
- 61A8E22C_DFL61_HARMATTAN_40.2012.13-7.DACH_EMMC_DACH

I did this actions (no screenshots taken):
- flasher -f -F main.bin -F emmc.bin --flash-only=mmc
- flasher -f -F main.bin
- flasher -R

The N9 has accepted the image, the phone has rebooted and has vibrated but now is died
Now the pc doesn't see anymore the phone via usb
I'm waiting the missing flex sensor, maybe this is the problem
In the meantime, I disconnected the battery

Thank you for the advice