If the verification process was freezing during the dual-boot, that could also be a hard disk error, with Endless OS happening to use a bit of the disk that doesn’t work properly in both cases. Can you try running a hard disk self-check? From the Endless OS USB stick you created, you can do this by choosing to “Try” Endless OS, then run the “Disks” application, select your hard disk, and in the menu select SMART Data and Self-Tests.