Paul, I see CM13 Marshmallow 6.0.1 is still around. I've had that on my main S4 for 12 months and it's been 100% stable. As I said earlier, 'nightly updates' were available until mid December when the guy who developed it passed it on to another crowd.
I have only just tried the Nougat 7.1.2 Android from Xenon on my spare S4 (was running Lollipop 5.0.1) and that was rated the best and seems to be stable at this point in time. I like the Recorder that is built in and the ability to record phone calls (incoming/outgoing).
I would suggest that if you want to try the latest (Xenon Nougat) that you do a Factory Reset which should wipe the phone clear of your previous attempt.
FYI.
If for some reason, your phone doesn’t boot up or you want to erase EVERYTHING on your internal storage and the phone for returning for warranty, you can do a factory reset using stock recovery.
Power off your phone (or pull battery for 15-20 seconds) Reinstall battery and hold down Volume Up and Power buttons together.
Phone will vibrate and show Samsung logo.
Keep holding down Volume Up and button but let go of Power button.
It will take a few seconds for the Recovery Mode to appear. Release the Volume button.
Once in stock recovery, choose “wipe data/factory reset”. Use the Volume Up/Down button to select required status.
Choose “delete all user data”. WARNING! This will ERASE EVERYTHING ON YOUR INTERNAL STORAGE!
Once done, reboot system.
Once rebooted, you should find your Galaxy S4 completely back to Day 1 when you got the phone, congrats!
For international GT-i9500 or GT-i9505, go to SamFirmware.com You will have to subscribe and sign in for an account (Free) and download the appropriate stock firmware for your model/country Galaxy S4.
Unzip the stock firmware, you should find a file ending in “tar.md5”. That is the stock firmware you will flash using ODIN.
I've included this for your assistance. If you do the Factory Reset, you will be able install TWRP using Odin.
Kies (Samsung) won't work on a 'rooted' phone.
If you need further help - let's know. Good Luck.