How to Unbrick the Galaxy S21 & Return to Stock Firmware?

In this article, we are going to show you how to unbrick the Samsung Galaxy S21 series. Not only are we going to show you how to unbrick the Samsung Galaxy S21 devices but we are also going to show you how to return to stock firmware.

One main example of a bricked device is that it’s in a boot loop cycle. There are many reasons why your device goes into a boot loop, such as you probably installed a root modification that was incompatible with your device or there is a bug. You may have installed an over-the-air update with a random bug in it, which causes your device to be unable to boot into the Android operating system.

No matter the reason, today’s tutorial will show you how to flash the stock firmware on the Samsung Galaxy S21 manually.

Turning Off the Device

Firstly, we recommend that you turn the device off or force the device to reboot. If your device is in a boot loop, it’s like constantly trying to boot into the Android operating system, restarting on it’s own, or maybe sending you into download or recovery mode.

• To start the process, press and hold the power and the volume down button for about seven to ten seconds. This will force the device to reboot.

Entering Recovery Mode

Hopefully the force reboot will send you into download or recovery mode, if not, try shutting the device off using the power button. Then, boot the Samsung Galaxy S21 into recovery mode using a USB cable and the power and volume-up button combination. If you are unfamiliar on how to do this, check this link, which includes the tutorial.

Performing a Factory Reset

If you have successfully managed to boot into recovery mode, you can then use the volume down button to change the highlighted option. We want to make sure that the wipe data/factory reset option is highlighted. Once that desired option is highlighted by using the volume up and down button, press the power button to select & execute that option. Tapping on the screen will not do anything; we need to use the power and volume up and down buttons.

Also Read:

How to Manually Update a Rooted Galaxy S21 and Keep Root Access?

You should get some information at the bottom, about wiping your device’s data. This means that it will format the data partition, the cache partition, the metadata etc.

Testing the Fix

After completing the factory data reset, you will return to the recovery mode main menu. Once the factory data reset process is complete, we can test if this fixed the boot loop issue. We can do that by highlighting the reboot system now option and then pressing the power button to select and execute that option.

It will cause the phone to reboot on its own and then attempt to boot the Android operating system.

This is the first step and attempt to try and fix a boot loop issue on the Samsung Galaxy S21 series.

If that fixes the issue, then great. You can just end the tutorial at this stage. This will not fix the issue for everyone though and some people will need to use download mode to flash the firmware file.

Downloading Firmware with Frija

To flash a firmware file using ODIN does not require an unlocked bootloader if you are only flashing the 100% stock official Samsung firmware. We can download the stock Samsung firmware from several places, like SamMobile, Frija, etc.

We however will use the Frija program to download the Samsung stock firmware.

It will take some time to boot back into the Android operating system after you have done a factory data reset. Just be patient and wait for the device to boot.

Preparing for Flashing the Firmware

• If you cannot boot back into Android, then we will try to boot the device into download mode. So that we can flash the firmware images with ODIN, as we mentioned before.
• To do that, we are going to power down the device again, just like before, when we needed to boot it into recovery mode.
• We can use the combination of the power button and volume down buttons if we need to force the device to reboot and turn off.
• To boot in download mode, power off the device completely. Then, plug the USB cable into your device while holding the volume down button. To learn more about how to enter the download mode, follow our previous tutorials.
• Then press the volume up button to continue into download mode.
• The goal is to get us into download mode so that we can flash some firmware images with ODIN.
• Download the stock firmware file on your PC. We used Frija to download the stock firmware file and if you don’t know how to do that, then follow our step-by-step guide to learn more.

The downloaded file is in zip format, and you have to extract the files in the same folder. After extracting, you will get the five different files that you need to flash to your device using ODIN.

Using ODIN to Flash Firmware

• Now, with our smartphone in download mode and whilst it is connected to the PC via a USB cable. You should see the “added” message in the ODIN log window.
• If you don’t, there is likely some type of USB-related issue; try using a different USB cable or USB port on your PC/laptop.
• Once you see that added message in ODIN, we can start loading the firmware files into ODIN.
• On the right side of ODIN, you will see four blocks, each starting with different letters.
• You need to load the relevant files in all these blocks to flash the firmware to your device.
• All you need to do is click on the first block, which starts with the letter “BL,” and a window will open. Now, you need to browse for the firmware files that you downloaded and extracted. Then select the file which starts with the letter “BL” to load in that block.
• Then click on the block with the letter “CP” and load the file starting with “CP.”
• Similarly, click on the block with the letter “CSC” and load the file that starts with the same letter from the extracted files.
• This CSC file will erase all the data on your device so that you can return it to the 100% stock firmware.
• In the end, click on the block with the letter “AP” and then choose the file with the same letters.
• Once all files are loaded in their relevant block, then click the start button at the bottom of ODIN. It will start flashing the firmware to your device. It will also take some time, so be patient.

You will get the progress log on the left side of ODIN and you can also see what ODIN is currently flashing and installing on your device. You will also see the progress bar at the top of ODIN.

Final Steps

• You will see the green pass message at the top of the progress bar once the process has been completed. It will also reboot your Samsung Galaxy S21 device on it’s own.
• Again, you will have to be patient while your device boots back into Android; it will take some time.
• Your device should boot back into the Android operating system, and you will need to set it back up as you did the very first time.
• Once you have set up your device, you will see everything has been uninstalled from your device. 
• You will no longer have Magisk installed on your device, if you had it from before for example. You will also no longer have root access(assuming you had all of these); you can check it by installing a root checker app.
• Everything has returned back to 100% stock firmware.

So this is the step-by-step guide on unbricking your Samsung Galaxy S21 device and re-installing 100% stock firmware back on your device.

Experiencing difficulties with your Device, check out our “How To” page on how to resolve some of these issues.