You must have bought this unit used. As far as I can tell they were manufactured from 2017 to 2019. As far as I can tell they actually had a pretty short run. There are reports of excess HDMI board failures in those units. I found out researching this that Marantz will only service their units for up to seven years from the date of manufacture, so the end of your repair options are drawing close.
I think it is debatable whether you spend the money on repair of that unit. It was a high end receiver but seems to have had a short manufacturing run.
Many members here will know that I would never consider buying a unit like that. I am firmly of the opinion that putting processing boards in the same box with 11 power amp boards and a power supply, is a thoroughly bad idea and the epitome of very bad design. In other words, I would expect a short working life from a unit like that. Members here will disagree and most inappropriately drool over units like that, where I would run in the other direction.