Preparations:

The hardware side and enabling developer mode.

• A Samsung A3/A5/A7 2017 Phone.
• Micro SD Card of a capacity of 3GB or more.
• Developer Mode Enabled(How to below).
• Samsung USB Cable & any PC or Laptop.

The enable developer mode procedure:

• Go to Settings.
• Scroll down to "About Phone".
• Software Information.
• Look for the infobox "Build number".
• Tap this 7 times, after 3 times you will get a notification "you are x tabs away etc"
• Head back to "Settings".
• Scroll Down.
• Select "Developer options".
• Enable: "OEM unlock".
• Enable: "USB debugging".

And you are done preparing to root and install a new OS to your Samsung A3/A5/A7 2017 phone. The next steps will be downloading the right software versions and utilities to root and install the Android Orea 8.0 OS. Below I will list and link all the files you need including a link to a zip file stored on my site to download all the files but for those security nuts out there I will provide a link per download so you can verify the content of each individual zip file.

Download the following files:

• Odin3: https://odindownloader.com/
• TWRP: https://twrp.me/Devices/Samsung/
• RMM-State Bypass Mesa: https://forum.xda-developers.com/samsung-a-series-2017/how-to/how-to-root-january-security-patch-sm-t3739225/post75360965#post75360965
• Magisk v18.x, Scroll down do not get the manager app: https://magiskmanager.com/
• HadesROM Oreo Stock V6.0 Final: https://forum.xda-developers.com/samsung-a-series-2017/development/rom-oreo-hadesrom-stock-t3779567/post78352504#post78352504
• Or download all files from my site(moved to google drive for better download speeds): https://www.hisevilness.com/downloads/download/6-miscellaneous-downloads/12-samsung-a3-a5-a7-2017-root-en-os-files.html