To enter into Developer Mode on a Samsung Smart TV you want to:
1. Press the Home button
2. go to Apps
3. Scroll down to settings
4. Press the 123 button
5. Enter 12345 as fast as you can
6. Select ON
7. Enter the IP Address of the computer you want to connect to the TV
8. Select OK
9. Turn off the TV by pressing the Power Button for 2 seconds
10. Turn the TV back on and you are good to go