That can happen particularly after a sudden power loss. Always use Halt system in Diagnostics or console option 6 when possible.
Connect a console, Reboot, press 2 for single-user mode at the "logo" menu, let it boot, press RETURN for /bin/sh, then run /sbin/fsck -y / a couple times until it comes back clean then /sbin/reboot.
I did have a power outage last week. Now attached to UPS.
Thanks for console info. Haven't tried connecting yet in that manner so now I have an excuse to do it :)