I noticed a couple of the caps on the main board were bulging at the top. Looks like the HDMI output is toast. Perhaps the caps are the problem. For now, I've worked around it by using an external HDMI switch which feeds the TV/PJ video directly and HD621 the audio portion separately.

Chris
Srces: Squeezebox Touch | OSMC Vero 4K+
Procs: HD621 > G61R > Minidsp DDRC-88D
Spkrs: 7200.2 + 5KC + 5Ks | iNuke6K > USC15 | iNuke3K > 2 x Crowson T108SS
Video: JVC HD950 & 1.9m React3 2.4:1 screen
Room: 5.8x2.8m | Various GIK Panels