Phone turned off for empty battery. Now it gives "No command"
I didn't really solve the problem, but I just tried to be sure that the phone was rebooting really from scratch (the purpose of resetting).

I went in recovery mode and I tried choosing "Power off" this time. After that it didn't try to reboot automatically as all the previous times.

I waited a little and then powered it on. Magically it booted correctly and without any issue