solar flares taking down power and internet grids isn't quite as scary as people might imagine.
it is pretty much only going to wipe out maybe a little over half of the global infrastructure, the chances of two of them hitting with neat 12 hour differences and making everything dark in one day is infinitesimally small.
so, a carrington event is gonna be big. but it's only gonna burn out the circuits of half the planet.
so also, that means bitcoin will keep running anyway.