Отопление и кондиционеры

Mitsubishi ducted unit shows E6 after a power outage. Indoor and outdoor units both have power. Anyone seen this?

Heat pump annual service before winter. Coil cleaned, refrigerant checked, condensate line flushed.

Two companies could not find why the second floor was cold. Nina found a disconnected duct in the attic in 20 minutes. House is warm again.