Scheduled a meeting, both parties were mute, and video did not work

[az8]

Scheduled a meeting, both parties were mute, and video did not work. I saw my guest for two seconds, then heard them, then all went mute. My camera below has a red mark and there was no way to get rid of that as unmute.

This was done on my desktop using a PC laptop.  

One time I was invited to a meeting and the same thing happened