When you flashed cf-autoroot-etc did you make sure it is for your model SM-G935F also called hero2-lte-xxx? Did you enable developer options > own unlocking and in the same menu USB debugging > on?
Did you flash a custom recovery after flashing c.f. Autoroot? You must have to get the recovery is not se android enforcing msg. It depends on the recovery you installed too. If it is TWRP then you have to remove the check mark from autoreboot in odin options, then press and hold home vol down and power, and immediately release vol down and press and hold vol up as the device screen goes black.
This will get you into recovery, if not then force reboot before it boots and again use the three button method to get into recovery. Once you are in twrp you will be asked if you want to modify system so put a check mark there by tapping it and drag slider to the right and you will be in twrp recovery menu.
The link should explain everything. You may need to read a lot so that you don't go on to discover that you cannot run certain apps as the don't run on rooted phones like Samsung pay, Samsung pass, and Ota updates.
You get the developer options menu by going into about phone> software info > build no and tap on build no 7 times then go back to the main settings page and you will see a new entry called developer options then follow steps above.
You need to follow each step given in the instructions to be rooted and have the phone boot normally. Here's a link describing what to do step by step