I also encountered the same issue. The "ENABLED, PW level HIGH, **LOCKED** [SEC4]" text comes from the smartmontools utility.
I was using Parted Magic (a USB bootable rescue Linux operating system) to secure erase a server-grade hard drive before placing it in a new machine. Sadly the secure erase process, once started, cannot be stopped and it can take 4-5 hours for the task to finish. I wasn't willing to wait that long for the machine to be usable so I ended up holding down the power button on my machine and forced shutdown the computer.
Upon rebooting, I checked the hard drive, and it was now in a semi-bricked secure state, I followed the "Disable Security" dialog from Parted Magic's "Secure Erase" tool (which is a GUI frontend to the command line smartmontools utilities):
This then allowed me to unbrick the hard drive and gain access back to it. I was able to successfully secure erase it later once I could give it 4-5 hours to do the operation. The hard drive was fine and no errors cropped up.
Parted Magic's web site also has documentation on what to do if a power outage occurs during a secure erase task. Google query their site and look for their "Secure Erase Selection Dialog" help page. I cannot mention the link here as I'll get marked as a spammer (I just signed up a few minutes ago just to respond to you so that others can see my response in future Google search queries against this "**LOCKED** [SEC4]" text).
Good luck to you and I hope this helped!
