Thanks for the suggestions, but I ruled all them out unfortunately. The player is connected to a 4k TV, and I did try almost all type of disks from CD to 4K UHD. And even if I can heard the disk spinning, the only output I can get is the blank HDMI screen of the Audio only HDMI, nothing from any other one, even the network led go off.
Actually, once I get the Home Menu text on the player display, it doesn't react anymore to any type of input, remote, front buttons. The only ones vaguely reacting are the power button, but like after pushing it 20 seconds and some RS232 commands, even if most are getting an "ER" response or their action is simply not performed.
It's like it just somehow crash always at the same moment during startup, not even showing any output on the HDMI. On my BP-103, as soon as it power up I get an oppo splash screen, but on this 203 ... nothing