popcornmix The user has video at HDMI-1, but not at HDMI-0.
Ah, in that case I agree. If no picture from HDMI-0 (but HDMI-1 works) on RPiOS, then there's likey a physical problem with HDMI-0 connector.
You should return Pi for a replacement.
The audio issue with Kodi using HDMI-1 is software (only hdmi-0 is supported, and that may be resolved with the LE 10 beta).
But still best to get the faulty Pi replaced.