This is a short sad post. After the work on the Quadra 610, getting the SCSI2SD card working, and doing a little cleanup, I made a mistake. I left the 610 running by accident over night, sitting at the “It Is Now Safe to Turn Off Your Mac” screen. In the morning, when I went to reboot it, death chimes.
I put the Quadra away for now, but it’s not looking good. I’ll see if some time off revives it, but I am a sad Mac restorer. It’s probably motherboard related since I have taken everything off of the motherboard just to see. I’ll loop you in if the status changes.