On the Clean boot did you install Norton First or did it come preinstalled?
If so try using Norton Removal tool to uninstall Norton before trying the update again.
Lastly I just tried the update and it failed obviously with the same error code or I wouldn't be here but I did check my updates and there were 2 optional updates doing those now and will then try the install again. Will post final results when achieved.
Also using GeForce Experience Program from Nividia to keep my 2 EVGA 660ti graphics cards updated will let you know if it helps.