My macbook pro has frozen completely whilst upgrading to Mohave

"My macbook pro has frozen completely whilst upgrading to Mohave

... It just keeps doing restarts"

Boot into Recovery (Command R) and from the dropdown menu: Utilities>  Disk Utility> run the First Aid on your Macintosh HD. If errors are found and repaired, run again until no errors reported.


Recovery http://support.apple.com/kb/HT4718

If need be you can reinstall the macOS from Recovery as well

Restart into recovery mode, choose Disk Utility, and Repair Disk.Run repeatedly until it comes clean or gets hopelessly stuck.

If it comes clean, try a Re-Install.

If not post back with the date of your Last Backup for more advice.