It's quite possible that the ONLY electronics that still would work after a Carrington Type Solar Flare event would be Cheyenne Mountain

 But, that likely would be the only place anything electronic would work then in the U.S. That might not be true of Russia or China or Great Britain or France or Pakistan or India. They might have underground hardened locations under mountains where nukes or Solar Flares wouldn't knock everything else out above 10 feet underground.