Found the problem and revived my phone. On the official huawei page there are 2 downloads, for cust 002 and cust 003.
At first I tried 003 cause it's written it's for Italy (where am I) : stuck at boot logo as cheetah.
Then I tried cust 002 and it worked!
Now I've flashed philz recovery and supersu:
To update to 350 I have to unroot and revert to stock recovery?