[Galaxy Tab 3 Q&A, Help & Troubleshooting] DevMyAndroid:
As you may know, KitKat has been released by samsung to the Sm-T210 / R devices. This update includes a new bootloader. This bootloader is VERY important to have when using a 4.4.X based ROM. It fixes offline charging and fixes a GUI bug in custom recoveries. In this thread I will teach you how to flash this Firmware to your device, and gain root access! I take no responsibility for any damages that may occur during or after the installation. Just follow the steps carefully and you should be fine.

Pre-update instructions 1

take note of your devices model number, this can be found in settings>> About device>> Model Number.

(If you are running a custom ROM your model number may not be correct. If this is the case, look on the right edge of the device, if you see a black square your model number is SM-T210R, if you do not have the square you have the SM-T210.)

NOTE: Make sure you have your tabs USB drivers installed to your computer. Download here http://www.mediafire.com/?jotj0yjj4st761t

Pre-update instructions 2

download Odin version 3.0.9 to your computer. Here is a link to Odin3.0.9 http://www.devfiles.co/download/CAHmXM6c/Odin_v3.09.zip

Pre-update instructions 3

Make a free account at http://www.sammobile.com/forum/register.php THIS STEP IS REQUIRED if you have the SM-T210R! Without an account you cant download the firmware file. Skip this step. No longer required as i changed the link.

Step 1

Download the firmware file for your specific model number.

SM-T210 firmware http://rapidgator.net/file/8c97131ca007ebcc7b57960b3c45b316

SM-T210R firmware http://rootjunkysdl.com/getdownload.../Firmware/T210RUEU0CNI1_T210RXAC0CNI1_XAC.zip

Step 2

now that you have downloaded your devices firmware and Odin, go ahead and launch odin. Now we will put your tab into update mode. You can do this by turning off your tab, then hold Power+VOL down+home when you see the words Samsung galaxy tab 3 release power BUT STILL HOLD VOLUME DOWN AND HOME! You will see a screen that says something like "Warning! Installing a custom OS may blah blah blah" just go ahead and click the volume up button.

Step 3

Now plug your device into your computer via usb cable and set your tab where it will not be disturbed. Now in odin click AP then find the update file you downloaded. This file will end in .tar.md5. Click the file and click open.

Step 4

Now that you have your device connected to your computer and the update file selected in odin, make sure re-partition is not checked and go ahead and click start. Please be patient, as this update may take a little wile to install. Once its done, it should say "PASS!"

Your device is now running android 4.4.2. If you would like to gain Root access,or install custom roms, continue to step 5! :)

Step 5

If you are reading this that means you want to use custom ROMs, or gain root access.. Now download this file to your computer. https://www.androidfilehost.com/?fid=23681161096069127

Step 6

Click AP in Odin and find the file you just downloaded, click open make sure re-partition is NOT checked and click start.

Step 7

After you see Pass! Unplug your tab and boot into recovery with the three button combo. From there you can flash custom roms!

NOTE: if you would like to Root your tab, complete all steps above and continue reading!!

Step 8

Download this file and put it on your SD card, http://download.chainfire.eu/396/SuperSU/UPDATE-SuperSU-v1.94.zip?retrieve_file=1

Step 9

Boot into recovery and click install zip>> click first option>> then find the file you downloaded. Once the file is found, click on it, press install.

Step 10

Wait untill it finishes and reboot your tablet. You now have SuperSu and root access!