You might need to connect the bottom ground posts together like in this video if some of them are not fully contacting the metal case
(Edit: posted by bassweight on YT
Some people will get lucky with this fix for a short time like i did, but then i dug abit deeper in to this problem. The problem is a row of 25v 100uf capacitors next to the relays on the top board with all the inputs and outputs. the capacitors are rubycon pk series and maybe denon bought a big batch of bad capacitors. You will see two relays next to the xlr outputs and some more further down the board, change the 25v 100uf capacitors next to the relays, it will stop this issue my advice is use 105c low esr 25v 100uf caps, when i measured the original capacitors they had halfed in capacitance and were around 56uf this causes the relays to chatter or vibrate causing loss of output or distortion.)