Can't update OS

[gordonbp]

Purchased a 32 GB 1 gen 7 yesterday - everything is fine except it won't update the OS!
It came with 4.2.2 and after I initially set it up, it told me there was an update available to 4.3 (Why not 4.4?)
It downloaded 157MB and then asked for re-boot.
On reboot it began the upgrade then half way through "Error". No explanation or reason, just "Error".
It then went on to the start screen, I opened it and it still showed 4.2.2.
Moreover every time I do Settings>System>About Tablet>System Updates>Check now it tells me the system is up to date.
I've cleared cached data, re-set back to Factory settings, and I still get this "Error" on installing, and the thing just goes round in circles.
How do I update?

[S.Prime]

Download Wugfresh's Nexus 7 toolkit and install the factory image for 4.4.4.

Sent from my Nexus 7 using Tapatalk