CONVERTER is the Charger. If you have 120vac at receptacles*, check Circuit Breaker for CONVerter in Breaker Panel?
If not tripped, there is a (pair** of 30a fuses, labeled REVERSE POLARITY) on POWER CENTER converter end of charge wire, and a 12vdc CIRCUIT BREAKER on battery end of same wire, (next to battery, with a RESET button on small end).
(* If no power to RECEPTACLES, check main breaker on GEN itself, usually right behind the Onboard START Switch); (**One = CONVERTER TO POWER CENTER Fuses, OTHER = FUSE PANEL to BATTERY.)