Preamble

This article will guide you on how to reflash your Samsung phone’s stock firmware if you are facing issues that require a full wipe of the OS. When done properly, it should be perfectly safe and have feasibly no risk of damage to your device. To ensure that, this guide instructs you to enable your phone’s protected state, which will NOT flash any unknown or incorrect binaries. However, please keep in mind, that this guide describes some sensitive processes, which - if done incorrectly - CAN cause permanent damage to your device.

I HOLD NO LIABILITY FOR ANY DAMAGE YOU MIGHT DO TO YOUR DEVICE.

Uses

Reflashing the firmware can fix issues that stem from corrupted OS files which wouldn’t normally get replaced/fixed using a standard factory reset. Another use is when you have an issue with updating your device, including but not limited to the settings app stating: Your current software version isn't supported. Visit a service centre. and refusing to download any new updates.

Dangers

Make sure to download the correct binaries, select every file correctly, and FOLLOW THIS GUIDE TO THE TEE. Deviating or making mistakes can vary from a simple error message to you owning a fancy paperweight. Don’t mess around with random switches if you don’t know what you are doing. Really.

  • Flashing an incorrect binary or messing around with random settings within Odin CAN brick your device.
  • Flashing an unofficial binary WILL trip the Knox e-fuse within your phone breaking all Knox functionality while also voiding its warranty. Only download official binaries to avoid this from happening.

Making the process safe

Samsung phones have two locks that exist to limit what binaries you’re able to flash:

  • An FRP (Factory Reset Protection) lock in place to not be able to flash any binaries on stolen devices which are still connected to a Google account
  • An OEM lock which ensures you can only flash official and valid binaries

If your phone has a Snapdragon chipset, it is permanently enabled. If your phone uses an Exynos chipset, you have to enable this in Android’s developer options. It should be on by default.

You can find out which chipset you have by downloading an app such as CPU-Z.

Prerequisites

Know your CSC code and model number

Samsung devices use CSC (Country Specific Codes) to differentiate firmware between different regions. It’s best you flash the same one as the one currently on your device for safety. An exhaustive list can be found here.

Warning: Some CSC codes are marked as Multi-CSC, these are NOT specific and represent several other CSC codes! If the CSC code you found in the first method is in the Multi-CSC section in the list linked above, try one of the other two methods.

Each phone also has a model number which defines the specific hardware variant you have, such as international versus USA specific hardware. You HAVE to match it to that of your phone’s, otherwise it will refuse to flash the binary.

You can find these code in a few ways:

  1. Dialing *#1234# and looking at the CSC field

    The first five letters are your model number, the following 3 letters are your CSC code. For example:

    • G988BOXMKHXEA
      • G988B is the phone model
      • OXM is the CSC code

  2. Using device information in your settings app

    • Model number:
      • Navigate to Settings > Device information > Look at the Model name field h
    • CSC:
      • Navigate to Settings > Device information > Software information > Service provider software version

    The CSC code will be listed in the bottom line, for example:

    ORX/ORX,ORX/EUX/ORX

    This means the phones uses the ORX CSC code, which equates to Slovakia. EUX is also mentioned, is the generic European CSC.

  3. Using the Phone Info app

    This app is still on the playstore, but doesn’t offer Samsung specific information anymore. The link includes the app with the additional information.

    • Model number
      • This can be found in the General tab, is in the Model field.
    • CSC:
      • This can be found in the CSC Code tab, is in the Active CSC code field.

Remove the device from your Google account

You MUST log out of all google accounts on the device in order to disable the FRP (Factory Reset Protection) lock. This feature exists so that stolen phones can’t be reflashed while still connected to a Google account.

Download Odin

Odin is a tool made for flashing Samsung devices, is what you will use to flash the new firmware onto your phone. You can download it here.

Getting the firmware binaries

To not trip (permanently disable) knox and void your warranty, you MUST install the official binaries. Several websites disseminate these such as Samfw and Sammobile, I will focus on Samfw given its faster download speeds via Google Drive.

  1. Enter your model number and click the entry that pops up
  2. Choose your CSC code
  3. Download the latest available version by clicking the Version field. Image showing the field to click
  4. Once downloaded, extract the .zip archive. It will have 5 big files inside as well as an info text file.
  5. Open Odin
  6. Reboot your phone into Download (Odin) mode by plugging it into your computer, rebooting, holding both volume up and volume down until your screen turns on with a warning. Hit volume up to continue.

  7. Verify your phone is visible to Odin by seeing if it pops up in the first ID:COM window. If it doesn’t, you need to install Samsung drivers found here.
    Image showing a blue IMG:COM window, indicating a device is connected

  8. Select everything but USERDATA accordingly from the archive you downloaded (AP_.. to AP, BL_.. to BL, CP_.. to CP, CSC_.. to CSC) and tick the box next to each one of these.

    You will have a leftover HOME_CSC file, which wouldn’t erase user data. However, we want a full reflash, so use the standard CSC_.. file instead.

    Image showing the above loaded into Odin

  9. In the config tab, enable Auto Reboot and F. Reset Time. ***TICK NOTHING ELSE!!!***
  10. If all files are loaded and your phone is showing up properly, you can hit Start.
  11. Wait for Odin to finish.

One of two results can happen now:

  • A green PASS lights up: Congratulations, you have successfully flashed your device! You can unplug it once it restarts, set it up as usual. If you had an issue with updating, you can verify it’s fixed now.
  • A red FAIL lights up: Something went wrong with the flash. Make sure you selected the correct files, have the correct model number downloaded.