So my brother-in-law called to say that while microwaving some food, the circuit breaker tripped.
He tried to reset it at the main panel but no matter what he did, electricity did not return to this particular circuit. To make the matter worse, it also tripped 80% of receptacles (including 2 other GFCI circuits).
We ran through multiple scenarios but the only thing I could figure out was that either the GFCI outlet or the Siemens circuit breaker was faulty.
Because this happened on Sunday late morning, I advised my brother-in-law to get an electrician in to take a look , rather than us mucking with it all day.
I will post additional information soon but in the meantime, I found a site with in-depth information on GFCI so I thought I’d share it here (http://www.thecircuitdetective.com/gfis.htm#bad)