Do you have problems upgrading Nexus 7 from Jelly Bean to Kitkat? Well I did, since the day got my hands of N7 device, it was unlocked and rooted.
Somewhere is Sep 2013 the News of Kitkat has been rolling out. In Oct my N7 device notified on the new Kitkat update. I have been trying using OTA update but each time came to "FAILED" installation and so decided to give up the idea since JB 4.3 was working fine.
Now Kitkat rolled out 4.4.2 version and still I had the same problem, did some researched on XDA forum and tried each of their suggestion but still did not work out. I was always stuck with "KoreanIME.apk" error on recovery, perhaps something I deleted earlier on.
Using Nexus Root Toolkit Ver 1.8
Finally decided to use the Nexus Root Toolkit (NRT). The last time used it was rooting the brand new N7. Run NRT and it started gathered information and upgraded to latest NRT ver 1.8.
With the new NRT version I decided to Flash Stock + Unroot, hoping I can do the update going back to stock. To my surprise NRT found the latest Kitkat 4.4.2 and installed on Nexus 7. Most of the data was lost but had earlier done a backup.
After that just like a brand new device, log in my account and immediately all the previous Apps started to download back to the device. After which followed by Root using NRT included Custom Recovery check, the rest just follow NRT instructions to install BusyBox and all is Done!!
Apps like Watsapp had to be installed manually since it does not support tablet version. Other data were also done manually.
I would not recommend this method unless you are prepared to wipe everything clean, so do a backup first. There were no other options and this was the only method.
Hope this helps.