@arubislander yes i did

@MrT10001 ok.
I've tried something different.
I've done a factory reset of Android 9 and after flashed that rom (founded on Xiaomi website)with MIflash.
No file corrupted, it worked nicely.
And here is the but, after the installation it still boot and crash in loop

@MrT10001 do you know what Android version is the one inside website rom?
I' ll try to download it from Xiaomi instead of the website.
If even in that case it will not work i'll send it to repair

@MrT10001 Same problem.
Can't load Android system, your data may be corrupt

@Tinninator follow up.
I've done the factory reset and tried again the installation.
I am back at the start. Boot and crash

@MrT10001 Same problem like last time i tried. I had there to choose the second option to let Android 9 start.

@MrT10001 Hi, first, thanks for all the help.
Second,even in both side (a and b) your command didn't work.
Using instead fastboot boot i managed to enter TWRP and do all your steps of point 1. (you need to start sideload and after launch the command otherwise it will give you error i saw).
Now I am withous OS, how do I install the rom on the 2 side?

@MrT10001 i am trying with MIflash, but it give me error: Can not found file flash_all.bat.
Can you tell me the steps to use TWRP correctly? Last time i' ve tried it told me the files were corrupt and i was force to make a factory reset

@MrT10001 it didn't work. it is still in the same loop

@MrT10001 i've checked the partition and it was already EXT4.
So it wasn't that the problem it seems