Nexus 7 (2012) won't update

[jringjr]

Help, I have a Nexus 7 (2012) that will not update to the next Android OS.
I currently have 4.4.3, but keep getting prompted that a new version (4.4.4) is downloaded and ready to install.
When I go through the steps to install, it goes to the "opened" robot and shows me a progression line showing it is installing, then half way through it gives me the red triangle over the robot with the word ERROR underneath. After a few moments it reboots and I'm still in 4.4.3 OS. It's now early December 2014 and I would like to eventually get updated to Lollipop (ver 5).
I'm not experienced with "rooting", but if I have to then I'll need the basic steps to make it happen.
Thanks for any help out there,
jringjr