Phone must be rooted. Install PhoneINFO.apk (attached). Everything will be in reverse so tap on touch screen accordingly. Open PhoneINFO. Tap on Menu icon (top left corner). At drop down, select Secret Codes, scroll down and find "2663" and tap on it. Tap on Launch 0. You’ll see black and white screen showing "Firmware Version" on top( if you don’t see, try to tap it few times). Tap on "TSP FW Update", then tap on "Touch key FW update". Restart phone and after that phone should be back to normal again. Hope this will help people who run into this problem.
How to Fix Inverted or Reversed Touch Screen After DRK Repair
I see quite a few people running into touch screen problem, as I had, after repairing DRK. Touch screen becomes inverted or reversed from left to right and vice versa. I did it on S6 G920T. This is how I fixed it.