Original post by: Les Bastides ,
Just updated from 4.1 to 5.1. Had already disabled sip. Copied expanded MacPro2009-2010FirmwareTool.zip from http://forum.netkas.org/index.php?action=dlattach;topic=852.0 to desktop and ran Mac Pro 2009-2010 Firmware Tool.app. Got error 5570. Downloaded MacProEFIUpdate.dmg from https://support.apple.com/kb/DL1321?locale=en_GB to desktop and ran again with success.