how to update software (rom) samsung S21 Ultra 5g

how to flash samsung S21 Ultra 5g firmware download

Welcome, dear followers, to a new lesson on your website, advanced settings. In this lesson, we will discuss the topic of updating the software or flash for the Samsung S21 Ultra phone. Mostly, we need to update the software or insert a new one if there is a problem with the phone’s software.

samsung S21 Ultra 5g firmware download
Why is my Samsung Galaxy S21 Ultra not getting updates
Or sometimes we may need to change the Samsung S21 Ultra phone because some applications may not work in old systems, and therefore the firmware system must be updated to be suitable for modern applications.

How to update the software ROM of the Samsung S21 Ultra 5G

In this lesson, our dear followers, we will need the firmware file for the Samsung S21 Ultra, and we will also need the Odin program, through which we will flash the Samsung phone.


After completing the download process, we unzip the firmware file for the Samsung S21 Ultra, and we also install the Odin program on the computer, then we turn off the Samsung phone and then press the volume increase and decrease buttons at the same time, then we connect the phone to the computer Via the USB cable, then we make sure that the phone is connected correctly, and after that we choose the four main files that we will include in the phone.

Follow with me the video below, which contains all the steps and stages that must be followed to flash the Samsung S21 Ultra 5G. If you like the video, do not forget to subscribe to the channel and share the lesson with friends in groups and forums.

The process of updating the firmware system of the Samsung S21 Ultra phone may take approximately half an hour. The phone should not be disconnected from the computer, as this may cause the death of the phone. We wait until the flashing process is finished, then we restart the phone and then verify that the firmware update is correct.

how to update software Firmware samsung S21 Ultra 5g with Odin Flash Tool

Updating the firmware of a Samsung Galaxy S21 Ultra 5G using the Odin Flash Tool involves several steps. This process is relatively straightforward but requires careful attention to detail to avoid any potential issues. Here is a step-by-step guide to help you through the process:


  1. A Windows PC: Odin is a Windows-based tool.
  2. Samsung USB Drivers: Install the latest Samsung USB drivers on your PC.
  3. Odin Flash Tool: Download the latest version of Odin.
  4. Firmware Package: Download the correct firmware for your specific model of the Galaxy S21 Ultra 5G.
  5. USB Cable: Use the original USB cable for best results.
  6. Backup Your Data: Flashing firmware will erase all data on your phone.

Steps to Update Firmware

1. Download and Install Samsung USB Drivers
  • Download the latest Samsung USB drivers from the official Samsung website or a trusted source.
  • Install the drivers on your Windows PC.
2. Download Odin Flash Tool
  • Download the latest version of Odin from a reliable source. Extract the downloaded ZIP file to a convenient location on your PC.
3. Download Firmware Package
  • Obtain the correct firmware for your Samsung Galaxy S21 Ultra 5G. Make sure the firmware matches your phone’s model number and region.
  • Extract the firmware ZIP file. You should see files with extensions like .BL, .AP, .CP, and .CSC.
4. Enable Developer Options and USB Debugging on Your Phone
  • Go to Settings > About phone > Software information.
  • Tap on Build number seven times to enable Developer Options.
  • Go back to Settings > Developer options.
  • Enable OEM unlocking and USB debugging.
5. Boot Your Phone into Download Mode
  • Turn off your phone.
  • Press and hold the Volume Down + Bixby (or Power) buttons simultaneously, then press the Volume Up button to enter Download Mode.
6. Connect Your Phone to the PC
  • Connect your phone to your PC using a USB cable while in Download Mode.
7. Launch Odin Tool on Your PC
  • Open the extracted Odin folder and run the Odin.exe file as an administrator.
8. Load Firmware Files into Odin
  • In the Odin tool, you will see several tabs: BL, AP, CP, and CSC.
  • Click on the corresponding buttons and load the extracted firmware files:BL (Bootloader) file goes into the BL field.
  • AP (Application Processor) file goes into the AP field (this file might take some time to load).
  • CP (Core Processor) file goes into the CP field.
  • CSC (Consumer Software Customization) file goes into the CSC field (use the HOME_CSC file to keep data, or CSC file for a clean install).
9. Start the Firmware Flashing Process
  • Make sure your device is detected in Odin (you should see an Added! message in the Log box).
  • Ensure that Auto Reboot and F. Reset Time options are checked in the Options tab.
  • Click the Start button in Odin to begin the flashing process.
10. Wait for the Flashing Process to Complete
  • Odin will now flash the firmware to your device. Do not disconnect the phone during this process.
  • Once the process is complete, you will see a PASS! message in Odin, and your phone will reboot automatically.
11. Initial Setup
  • After the phone reboots, it may take a few minutes to start up for the first time.
  • Follow the on-screen instructions to set up your device.

Important Notes

  • Ensure the firmware you download is for your exact model and region to avoid bricking your device.
  • Flashing firmware will erase all data on your phone. Ensure you have a complete backup before proceeding.
  • This process can potentially void your warranty or brick your device if not done correctly. Proceed with caution.

By following these steps, you should be able to update the firmware on your Samsung Galaxy S21 Ultra 5G using the Odin Flash Tool successfully.

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