I guess the best thing to do would be to go to the Denon site and find the closest Denon Service Center and see if they even have the necessary parts ( HDMI board ) to do a repair. I have a 5308ci and the parts are all but gone for that unit. I'm 240 miles away from a Super Service Center and have had to make the trip twice, once for repair and once for an upgrade.
Denon AVR X7200WA, Emotiva XPR-5, Emotiva XPA-7, Sony XBR 75" 850C, Oppo BDP-103D, Roku 4.
DefTech BP7000SC (L/R), CLR3000 (C), SM55 (FH), UIW BPZ/A (SB), UIW 75 (TM).
JBL L7 (Sur), EoSone RSR 350 (RH).
PC 2.1 setup. Emotiva Stealth 6, SVS SB2000 sub, Emotiva DC-1 DAC.