CNBC reported that SpaceX scrubbed the launch of its Starship mega rocket on Thursday, with CEO Elon Musk pledging to make another attempt hopefully in a few days.A 90-minute launch window opened at 6:45 p.m. ET, and within minutes the company announced on a livestream it was standing down. Musk wrote on X that some of the engines didn't start, triggering an automatic launch abort, adding that two Raptors will be removed and replaced with most probable launch timing early next week.Shares of SpaceX fell more than 3% in extended trading, sinking further beneath its $135 IPO price. The stock is on a five-day losing streak, closing at $131.11 on Thursday.The rocket was poised for takeoff from SpaceX's Starbase complex in South Texas when a hold was triggered on the booster, shutting down engines right as they were starting to ignite. It would have been the second flight of the upgraded Starship V3 since the June IPO.An earlier V3 test in May saw several booster engines fail to reignite for a soft landing, causing it to plummet into the Gulf of Mexico. The FAA ordered an investigation and cleared Starship to fly on Monday, citing heat effects on propulsion components and erroneous engine alarm settings as root causes.SpaceX identified four corrective actions including hardware and software updates. Thursday's mission planned to ferry 20 next-generation Starlink satellites to connect with the broader constellation.Investors are closely watching the 13th Starship test as the rocket is key to scaling Starlink and completing NASA Artemis moon missions. SpaceX's $85.7 billion IPO was the largest on record.