The Starliner capsule had stood ready for blast-off from NASA's Kennedy Space Center in Florida on Saturday before a ground system computer triggered an automatic abort command that shut down the launch sequence.
NASA said its teams worked overnight to assess the ground support equipment at the launch pad that encountered issues during the countdown and identified an issue with a ground power supply within one of the chassis which provides power to a subset of computer cards controlling various system functions.
The chassis containing the faulty ground power unit was removed, visually inspected, and replaced with a spare chassis, the space agency said.
The CST-200 Starliner's first crewed voyage to the International Space Station (ISS), with two astronauts aboard, remains a key milestone for Boeing as it scrambles to gain a greater share of lucrative NASA business now dominated by Elon Musk's SpaceX.
Once launched, the Starliner is expected to arrive at the space station after a flight of about 24 hours and dock with the orbiting research outpost some 250 miles (402 km) above Earth.
