7.1.1 recieved OTA google update "Verification failed" nexus 6p?

[AC Question]

Nexus 6p update 7.1.1 verificaton failed??? New to droid and not a developer I bought from pawn shop this summer. Showed software up to date and sim worked calls/data on cricket network. Phone running dirty unicorns? ROM? SuperSU? No clue DU? Read about Nexus/google sending monthly security patches/updates but nothing here since may,1 patch phone showed being done week before i bought the phone? Finally like 12/6?7? received a system update "7.1.1" day after they began rolling out to 6p's from what I think I maybe understand:/? So clicked on update which " fixes crucial bugs and improves stability and performance for your nexus 6p." 1270.1mb file "OK" starts the "downloading" showing as status bar slowly showing progress moving left to right. Half hour later+/- download completes "Verification failed" ??? Nothing updated goes back to update screen loops thru the process downloading 30+/- minutes or so then same " verification failed" Need help securing phone/personal data etc making it my own praying my privates life still private (besides google) and that I'm not owned!?! Hoped update would return me to factory settings along with my peace of mind but without verification maybe unicorns have a point:/