I've searched for a way to shut the display off on a yamaha receiver. I have a pronto neo remote and if their was a code to shut it off i could program it onto there.
If there isn’t a button on the remote, a menu option or a mention in the manual then you’re out of luck, Albert.
If the display is too bright you could pick up a piece of scrap window film from a tint shop (35 or 20% would probably do it) and cut it to fit the display. I’ve successfully done this in the past with overly bright displays.