I hit the same issue. I logged into it via HDMI/keyboard and found that wlan0 isn't even seen as a link anymore. Likewise, it doesn't hear or respond to anything, but I think services are running. It does try to speak to me when I use the button on it, but there's no audio. This makes me think both the wlan and audio drivers are missing. This makes me think the upgrade of packages removed some driver-related ones. I looked at the apt cache on the system and didn't see any packages from the original build to revert to (or maybe I missed them), so I think I'm just going to grab the image from here: https://docs.mycroft.ai/mark-1 (bottom of page), open up the case, and re-burn the image onto the SD.
There's probably some apt pinning that needs to be done to avoid having people do this when it's more finalised.