Yesterday I had to reflash the stock KDZ after some issues. I flashed v20a and after it booted it got an update to v20c software.
I then tried to root it but failed by using any method from here.
Using update.zip from external SD card always ends up with an "E:failed to mount /sdcard (invalid argument)" error.
I tried using ext 2/3/4, using two different SD cards, and trying tools on windows and Linux (Ubuntu desktop).
Purple Drake Method wasnt working. One Click root I found on XDA wasnt working.
At the end I stumbled upon a youtube video of a guy using KingRoot. Downloaded apk from description of that youtube video and succesfully rooted the v20c software.
If anyone needs it I attached the apk I used on this post. I see on their site that there is a newer version but I only tried this one.