Factory reset failed

Terminate install. First try the Cancel. If that does not work press and hold the Power button until it shuts down and startup and see what happens.

If still stuck then terminate and then boot to Recovery, use the Recovery Disk Utility and repair/First Aid the startup disk and reinstall macOS via Recovery.

How to reinstall macOS - Apple Support

Was this method used from Apple >> Use Disk Utility to erase an Intel-based Mac

Was this method used from Apple >> How to reinstall macOS

Follow these guidelines during installation:

• If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
• If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
• If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.
• Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.