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    Samsung Galaxy S21 (SM-G991B) - COS - G991BXXS9EWF3 firmware

    Samsung Galaxy S21 firmware G991BXXS9EWF3 is the Android 13 build for the Samsung Galaxy S21 (model SM-G991B), released by Samsung for Greece (Cosmote) (COS). It was built on 21 June 2023, carries the 2023-07-01 Android security patch, has changelist 26203421. The package combines system build G991BXXS9EWF3 (AP/PDA) with CSC build G991BOXM9EWF3 for the COS region code. SamMobile added this file to the firmware archive on 10 July 2023.

    Country
    Model SM-G991B
    Product Code COS
    Security Patch 2023-07-01
    OS Version Android 13
    PDA G991BXXS9EWF3
    CSC G991BOXM9EWF3
    Build Date 2023-06-21
    Changelist 26203421
    Join to Download Fast download

    G991BXXS9EWF3 for other regions and carriers

    The same G991BXXS9EWF3 build is also available for these SM-G991B regions:

    Other SM-G991B firmware for Greece (Cosmote) (COS)

    All SM-G991B firmware for COS · All Samsung Galaxy S21 (SM-G991B) firmware

    How to flash G991BXXS9EWF3 on the Samsung Galaxy S21 (SM-G991B)

    We recommend updating through Samsung's own tools: over-the-air (Settings › Software update) or Samsung Smart Switch on a PC. Flash the full firmware with Odin only when you are sure about the risks. A wrong region or a failed flash can brick the device, and SamMobile is not responsible for any damage.

    1. Download the firmware package above and extract the ZIP. It contains the AP (PDA), BL, CP and CSC files, plus a HOME_CSC file.
    2. Download and extract Odin on a Windows PC, and install the Samsung USB drivers if the PC does not detect the phone.
    3. Switch the device off and boot it into Download mode (usually Volume Up + Volume Down while connecting the USB cable, or Volume Down + Bixby + Power on older models).
    4. Open Odin. The ID:COM box turns blue when the device is connected.
    5. Load the files in their slots: BL, AP, CP and CSC. Use HOME_CSC to keep your apps and data, CSC to wipe the device.
    6. Leave Re-Partition unticked and click Start. The device reboots when Odin shows PASS. The first boot after a flash can take a few minutes.

    Step-by-step PDFs: 5-file firmware and 1-file firmware.

    What the build numbers mean

    PDA / AP (G991BXXS9EWF3) is the Android system build; its last three characters encode the year, month and revision. CSC (G991BOXM9EWF3) is the region and carrier configuration, and CP is the modem firmware. The product code COS identifies the region or carrier this package was made for (Greece (Cosmote)). Flashing a package for a different product code changes carrier features and can be refused by the bootloader, so pick the one that matches the CSC shown under Settings › About phone › Software information.