So if some of you are looking for a 'how-to' guide, look no further!
-I don't take ANY responsibility if you bricked your device during the flash!
-Follow the guide below before flashing your official firmware using Odin!
On the phone
-Sign-out any accounts on settings
-Have OEM-unlock & USB Debugging ON (developer options)
-*optional task, just in case* Screenshot your device information on the settings tab (IMEI, Baseband, Software Info, Model number)
-*optional task, just in case* Backup your device using Samsung SmartSwitch software
Things to download
-For this guide I used Odin v3.13.1 https://dl.sammobile.com/Odin3-v3.13.1.zip
-You can install the Samsung driver using SmartSwitch if your Win PC can't detect your Samsung phone (it should show on Device Manager > Modem > something like Samsung Modem)
-*READ* You can't flash back to version 6.0 now because of (Android Oreo 8.0 is using different version of boot-loader) but there are some late Android 7.0 with updated boot-loader, those are using boot-loader binary v2, so binary v1 it will be conflicted and won't work upon flash.
-*NOTE* Download the correct firmware of your phone model by following the baseband, that's why I recommended to take screenshots of your phone, you can search it on here https://www.sammobile.com/firmwares/, for mine, I've searched SM-G935F and BTU is my choice, the filtered results should be your correct firmware. But in my case I used (v7.0 in March 2018) because it has the binary boot-loader v2 with it (whatever it called, it's important otherwise it will not work which I've tried)
-*optional*, if you find sammobile download speed is way too slow* You can use https://updato.com/firmware-archive-select-model?q=SM-G935F&exact=1&r=&v=Nougat%28Android+7.0%29%2COreo% 28Android+8.0.0%29&rpp=100, and basically look for the correct firmware which I have mentioned above.
-Extract your firmware onto a single folder, don't mess them up! (you should see something like AP_G935blahblahblah.md5, and you will need AP_, BL_, CP_, CSC_ for downgrading)
Follow the steps:
1. Now you have the correct firmware and Odin running on Admin right
2. On Odin you can add AP_, BL_, CP_ & CSC_ onto the correct selection, for example: https://i.imgur.com/DIB2d1S.png
3. Have your phone on Download mode, google it if you don't know how (make sure you followed the On the phone step first, it's very important)
4. Find a data USB cable and plug into USB2.0 port, make sure your phone appeared on Odin (you will see something like 0:[COM5])
5. On Odin (only Auto Reboot, F. Reset Time) is needed, it should be ticked by default.
6. Now you can safely click 'Start' on Odin.
7. DO NOT TOUCH YOUR PHONE in case your USB is loose which I had experience before.
8. Wait until it shows a green PASS! like this: https://i.imgur.com/FYosmx2.png
9. When see a blue screen with Erasing text on it, please wait until it reboot and hold (Volume UP + Home Button + Power Button) boot to recovery mode
10. Wipe cache partition, and data/factory reset then reboot system now
11. Wait for it to boot into your sweet sweet Android Nougat 7.0 (Late version)
12. Disable auto-update if you wish, mine was on auto-update so I had to pause it half-way
Hope you find this guide helpful, I tried to remember the steps on my head as I typed, (*sorry for the grammar if you find it hard to understand) and if you think I've missed something here, let me know! I would update the guide if any step is missing, just in case