Hello,
Yes, you are correct. There's a possibility the error message 0x1f01df may be due to malfunctioning firmware and other hardware components. Usually if the computer is unable to properly shut down, it cause an issue with your hardware. That's great that you performed a startup repair and then have the result of 0x0. It means that the issue with your computer has been repaired already. Are you still experiencing any issue after performing a startup repair? If yes, what's the behavior of your computer?
Regards.