Thanks for posting! I’ll try to answer step by step:
We have had this issue with some devices exposed to high humidity conditions, and in other cases, with a hardware problem. In the first case, the microphone comes back to life after a little while, but not in the second. So if it persists, the best is to email firstname.lastname@example.org for hardware problems
This one won’t change much, since the normal atmospheric pressure is always around 101kPa next to sea level, except when there’s a storm coming or a heat wave. Generally, lower barometric pressures indicate a storm, and the opposite for the heat.
Regarding this, there is a firmware issue that has been fixed as explained here.