Ah, that’s a bad sign and probably a bad motherboard.
I’m just another user, but I’ll tag @support for this.
FWIW - If it is the motherboard and since it looks like you might be out of warranty, if you want to have a dedicated device to run Roon then it will probably be cheaper to get an Intel NUC and install ROCK, rather than getting the Nucleus repaired.
My Roon core won’t start up. I have tried resetting the battery bit still no luck. The power button lights up but nothing else, it is not visible on the network.
Sorry to hear about the trouble with the Nucleus here. If there is no HDMI output, it is likely a sign of a motherboard issue. I’d be happy to get an RMA started for you so that we can resolve this issue, I’ve followed up via private message to gather purchase and shipping details, thanks!