It caused extensive damage in the rear of the plane and scorched the top of the outer skin of the fuselage.
Japan’s ANA Holdings Inc, which operates the world’s biggest fleet of Dreamliners, said last week it found damage to the battery wiring on two 787 beacons during checks.
Damage was slight, but the beacons have been sent to Honeywell for inspection, ANA said.
Qatar Airways meanwhile denied that one of its Dreamliners had caught fire after industry sources said smoke had been reported near an electrical panel, while the plane was on the ground in Doha.
The aircraft has not flown since July 21, according to web tracking data, an unusually long downtime for an active jet.
“I can unequivocally say that there was no fire. It was just a minor issue, not even an incident. We’re working with Boeing to get it fixed very soon,” an airline spokeswoman said.
No timeline for the repair was available.
Boeing declined to comment.
(Additional reporting by Tim Kelly and Regan Doherty; editing by Stephen Coates and Tom Pfeiffer)