Power off your Samsung phone.
Press and hold the power, Bixby and volume down buttons until you boot into an Android screen.
Navigate using the volume buttons and select to pass the splash screen. You should be in Download Mode.
Open Odin and select AP.
Select the AP_ TAR.MD5 file from the Samsung firmware download. Make sure to select the largest of the files if there are more than one. Wait for Odin to load the file.
Select Start in Odin to begin the flash. If Start isn’t responsive, unplug the phone from USB and reconnect.
Allow Odin to work its magic. Your phone will reboot into stock Android once done.
It’s vital that you follow each step exactly as you are essentially replacing your entire operating system. If you follow the instructions and select the correct firmware from Samsung everything should go okay.