Screwed up s5 firmware

A

AC Question

I am using a Samsung Galaxy S5 G900A. I was unsatisfied with android 5.1.1 so I decided to downgrade. I followed this method: htt p: //forum .xda-developers. c o m/showthread.php?t=2785363

Now my phone says: "Firmware upgrade encountered an issue. Please select recovery mode in Kies and try again."

Kies says that the connected device is not supported. However, Odin still detects my device, but keeps failing to load Android KitKat. At this point, I don't care what firmware I'm using as long as I get my S5 back to normal. Please help.