I’ve tried using the pi 3b+ with fold for covid and all I see is a blank screen either on the official display or via HDMI. I’ve tried two separate pi’s and I am sure that the card isn’t corrupted as different OS’s load on it just fine.
If you are using the official image, then this is all that you will see other than sometimes the Balena logo.
You access the system via a web browser using http://foldforcovid.local/ (assuming this is the only one, otherwise it will be http://foldforcovid-2.local/ then -3, -4 etc) or the IP address. Then you will see a screen something like this
Oh. I was assuming that the screen would appear as a display on the Pi
The gui screen sometimes appears on the console but the keyboard and mouse don’t appear to work so it has limited usefulness. I doubt this will be changed so I would stick to use the web gui at least for now.