Posted by Gnomad on Mar 10, 2016; 3:40pm
URL: https://itus.accessinnov.com/Use-system-restore-to-install-hotfixes-tp380p390.html

Sounds reasonable, user8446 also suggested it here.  However, I just did a test "restoring" from a tar.gz that contained a single file /etc/test_BAD, and after the subsequent reboot the file was not present in the Shield's folder structure as I'd expected.  So the restore script may be doing something more than a simple tar -zxvf.  

Signing off for the night, but let you know if I get round to investigating further - insights from anyone else appreciated!