I have problem with mac os x high sierra
The system stops in the progress bar.
Try restarting and hold down the Shift key until you see the Apple symbol.
Does it finally boot (it will take longer than normal)?
If it does boot, try restarting normally.
Use safe mode to isolate issues with your Mac - Apple Support
Old, but possible utility: macOS Sierra: If your Mac stops or delays while starting up
To reset the startup disk without being able to boot, reset NVRAM: