Update from BBC website:
"Earlier reports that smoke was seen in the cockpit were inaccurate, ANA said. The pilots saw a warning on their computer screen telling them there was smoke inside one of the electrical compartments, the airline said. The source of the smoke is not yet known.
The pilots also received a warning that there was a fault in the battery system. ANA said the battery in the forward cargo hold was the same type as the one involved in a fire on another Dreamliner at a US airport last week."