A Japan Airlines Boeing 787 Dreamliner may have experienced a battery-related problem during a flight early on Sunday.

It would be the first reported issue of its kind since electrical systems on the trouble-plagued aircraft were upgraded earlier this year, the Financial Times reports

Jal said cockpit indicators on the aircraft, which was flying from Helsinki to Tokyo, warned of a problem with the lithium ion battery that supplies the aircraft’s auxiliary power unit, though no damage or fault was found.

The battery involved in Sunday’s incident was of the same type that burnt on two 787s early this year, causing a global grounding of the fleet in January.

Service resumed after the batteries and related systems were modified in April and May, and since then there have been no reports of problems.

Jal said it had allowed the Helsinki-Tokyo flight to proceed normally following the warning after it determined that there was nothing wrong with the electrical current or voltage in the auxiliary power system.

The aircraft landed in Tokyo without incident, and maintenance crews found no obvious physical problem with the battery, which was replaced, raising the possibility of a fault in the warning system rather than the battery itself.