BuzzBox
If we use the oxygen bottle rupture on QF30 as a guide to the immediate blast area damage, then the L GCU and L BTB are not in the direct “blast” area.
The Left Main AC Bus (ie power to SATCOM) may have been isolated automatically because of a fault caused by the oxygen bottle rupture, or the crew, who were overwhelmed by failures, have conducted the ELEC AC BUS L checklist or depowered/repowered the Left Main AC Bus in an attempt to restore lost systems.