Plugged in the battery? If your speaking of the battery on the trailer then, that is the issue. Your shore power will power your outlets, MW, Electric water heater, AC but your lights run on 12 volts. The shore power will charge your batteries but, the battery needs to be connected for them to work. Also fan on heater works on battery, along with other devices
Good Luck and congratulations !
2011 Toyota Tundra double cab