If you have the linear power supply then you are much less likely to have a power supply problem. You could check the 5v and 12v lines where they emerge from the capacitor board ( the multi way connectors near the motherboard) but I would first reload the firmware, type the unit and then try again. If that doesn't get you anywhere try removing all cards from the unit except the bare minimum (one input card and one output card only) just in case you have a card failing. It wouldn't eliminate those cards of course, nor the internal processing cards, but it might narrow down the variables a bit. I had elusive trouble with an ID40. It crashed as soon as I asked it to play audio but everything else in the 861 seemed ok. It turnrd out to be a rogue tape card. When removed everything was perfect.

Cinema/Music: Trinnov Altitude32 8-16,218,Cloud 4 channel, Marantz UD5007,DSP5200SE(2+C),DSP3300(4),DSW(2),271,MShort Ceilings,AppleTV 4K
TV: Marantz SR7013 Wharfedale Diamond 9x4+Celestion(C)
Music: Roon,i7NUC8gen,QNAP TS253A, Sony Scala, MS200, Garrard DDQ650,Wharfedale Diamond 12.3
Kitchen: AD88 (bluetooth via i80).