I have exactly the same software specifications (V50020a) and Build-Number (KOT49I.V50020a) and this is what I did.
Tablet: Security- activate unknown sources, Developer options - USB-debugging enabled
Computer: download and install USB-drivers for LG G Pad 8.3 http://www.lg.com/de/service-mobil-telefon/lg-G-Pad-8.3
1. Root with Tovelroot V2 http://towelroot.com/
2. Install SuperSu v2.00 http://forum.xda-developers.com/show....php?t=1538053
3. Start SuperSu and Update Binaries ( normal)
SuperSu says failed to update Binaries please reboot, rebooted
after reboot Supersu works fine.
4. Install SdFix http://forum.xda-developers.com/show....php?t=2684188
should work without problem, if not you have a problem with root.
5. Install Flashify http://forum.xda-developers.com/show....php?t=2349847
Backup kernel & recovery , just in case.
I did NOT use this to flash the new recovery, but later on to enter in the new recovery
6. Download the newest version of TWRP for v500 from here http://forum.xda-developers.com/show....php?t=2551499
Attention !!! you have to take the one where it says:" These builds are for the 4.4.2 bootloader"
download new version 18.104.22.168 !! 4.4.2-v500-TWRP_22.214.171.124-recovery.zip !!
copy the recovery.zip to your tablet
7. Download the tool to flash recovery from here http://forum.xda-developers.com/show....php?t=2698267
look at step 3 , download: V50020_aboot_twrp_v2.zip, to your computer and unzip it.
8. Connect the tablet (MTP) to the computer and run file:runme.bat, ! on tablet you have to allow acess from the computer and SuperSu acess for adb !
when finished disconnect usb and let the tablet reboot
9. On the tablet start Flashify , in the menu press: reboot to recovery
10.Tablet starts to the TWRP-recovery. Now go to:install and flash the new version of twrp(126.96.36.199) that you have copied to the tablet.
this worked for me.
Edit: For all who have the new V50020d firmware
you have to modify the runme.bat file before you run it!
Have a look over here, post 72
change the V50020b to V50020d, dont forget to save the file.