Root a Samsung Galaxy 4 tab 7", Kies isn't working I am trying to root a Samsung Galaxy 4 tab 7". The box says SM-T230NU with a label "Model: SM-T230NYKMXAR".   

I got drivers from here:
http://www.samsung.com/us/support/owners/product/SM-T230NYKUXAR
which is slightly different number (has a U instead of M) but matches (ie. Samsung Galaxy Tab® 4 7.0 8GB, Black). I installed these and the device connected to the PC with no problems.   

Using Odin 3.07, it detecets the device. I click the PDA button and select CF-Auto_Root.tar, then Start and I get this error:

 Firmware update start..
 recovery.img
 NAND Write Start!!
 cache.img.ext4
 FAIL!
 All now when I restart I get this message:

Now when I restart I get this message:
Firmware upgrade encountered an issue.
Please select recovery mode in Kies &amp; try again.threads completed. (succeed 0 / failed 1)    

I downloaded and installed  Kies 3. When I run it it says "The connected device is is not supported by Kies 3".
It should be, this is 4.4 KitKat  

So I tried Kies 2.6, and it doesn't connect either. It doesn't give this error message, just keeps trying to connect but doesn't.

What can I do now?
Flash your stock ROM using Odin whilst your device is in
Download mode  Power  +  Volume Down  +  Home 

(Put the file in the AP/PDA depending on what version of Odin you have). If this works then your tablet may be back to factory state, but if it fails then you have Hard bricked your tablet. Presuming it isnt bricked, use the latest .apk file of King Root to root your Sm-T230. 

Stock Rom Download from XDA forums: ACHERON ROM v2.1.1 and
Odin 3 download