Hi
I tried a number of reboots, both from the console and by power cycling, all without any success. My upgrade to 5.0.16C was back in 2020 so that isn't the issue. That said, I did move the ISY994 to another part of the house as its old location was being renovated. I expected to have to heal the Z-Wave but I can't even talk to the dongle.
Like you said, the board could be going bad but I'll try reseating it incase the travel across the house was hard on it. If that doesn't work, I guess I better order the new 500 series board.