While in the Server-Manager, I attempted to restore a directory of files.  After selecting the most recent rotated backup, I hit "next" hoping to find an option to filter for the files I wanted.  Instead, it went into full restore mode.  I was afraid to stop it, and let it go on for a full restore, but it stopped at one file.  I left it a couple of hours, but clearly it was not progressing further.  I exited the Restore mode to another part of the Server Manager where I was warned that the system needed a reboot, else would be unstable.  I rebooted, and the reboot halted with the warning that the restoration had been incomplete and I should consult the user manual.  Repeating this gets the same result.  My system is down.  I see no references in any of the online documentation.
Why did the restore hang?  What necessary steps must I take to restore my system?