How to Unroot the Samsung Galaxy Alpha SM-G850M

Unrooting the Samsung Galaxy Alpha SM-G850M restores the phone to its original factory state, removing root access and reinstalling the stock Samsung firmware. This is necessary if you want to receive official over-the-air updates, use banking apps that detect root, or send the device in for warranty service. Before starting, back up all personal data, as the process wipes the internal storage completely.

What You’ll Need

A Windows PC (the required flashing tool does not run on macOS or Linux without a virtual machine)
The original Samsung USB data cable that came with the phone
The stock firmware file for the SM-G850M (search for “SM-G850M firmware” on a site like SamMobile or use the Frija tool to download the correct CSC region file)
Odin3 software (version 3.13.1 or newer, version 3.14.1 is commonly used)
Samsung USB drivers installed on your PC
A fully charged battery (above 70% is recommended)

Step-by-Step

Back up your data. The flashing process wipes the phone. Use Samsung Smart Switch, Google backup, or manually copy photos and documents to a computer or SD card.
Download and extract the firmware. Download the correct SM-G850M stock firmware for your region (CSC). Extract the ZIP file. You should see a file ending in .tar.md5 (or just .tar). Do not extract that file further.
Install Samsung USB drivers. If you have not already, install the Samsung USB driver package on your PC. Restart your PC after installation.
Download and extract Odin3. Extract the Odin ZIP file to a folder on your desktop. You will see Odin3.exe and possibly a few DLL files.
Enable USB Debugging. On your phone, go to Settings > About Phone > tap Build Number seven times to unlock Developer Options. Then go to Settings > Developer Options and enable USB Debugging.
Boot the phone into Download Mode. Turn the phone off completely. Press and hold Volume Down + Home + Power buttons simultaneously. When the warning screen appears, press Volume Up to continue into Download Mode.
Connect the phone to the PC. Plug the USB cable into the phone and PC. In Odin, you should see a blue or yellow box in the top-left corner saying Added!! with the COM port number. If you do not see this, reinstall drivers or try a different USB port (preferably a USB 2.0 port on the back of the PC).
Load the firmware into Odin. Click the AP (or PDA) button in Odin. Navigate to the extracted firmware folder and select the .tar.md5 file. Do not touch any other buttons (BL, CP, CSC).
Verify Odin settings. Ensure that only Auto Reboot and F. Reset Time are checked in the Options tab. Re-Partition must be unchecked.
Start the flash. Click the Start button in Odin. The flash takes about 2-5 minutes. You will see a progress bar in the top-left and a green PASS! message when it finishes. The phone will reboot automatically.
First boot. The first boot after flashing takes longer than normal (up to 10 minutes). Do not interrupt it. Once it reaches the home screen, the phone is unrooted and running stock firmware.

Common Mistakes

Using the wrong firmware. Flashing firmware from a different model (e.g., G850F instead of G850M) will fail or cause a bootloop. Always verify the exact model number in Settings > About Phone before downloading.
Re-Partition checked. Leaving this option enabled will attempt to repartition the phone with a PIT file, which you are not providing, causing a hard brick in some cases.
Unplugging the cable during flash. Any interruption during the write process can permanently damage the bootloader. Keep the cable firmly connected and do not touch the phone until Odin shows PASS.
Using a USB hub or front-panel port. These can cause unstable connections. Use a rear USB port directly on the motherboard.
Forgetting to disable Samsung’s anti-theft. If you have a Google or Samsung account active, the phone will ask for the previous credentials after reboot (FRP lock). Remove the accounts in Settings before flashing, or have the credentials ready.

Tips

Write down your Google account email and password before starting. If the phone asks for them after the flash (Factory Reset Protection), you will need them to get past the setup screen.
If the phone was rooted with a custom recovery (like TWRP), flashing stock firmware via Odin will also replace the recovery with the stock one. This is the cleanest way to unroot.
After the flash, check for root by installing an app like “Root Checker” or simply try to open a banking app that previously refused to run.
Keep the firmware file on your PC in case you need to reflash later.
If you plan to root again in the future, note that the bootloader may be locked on newer firmware versions. Unrooting does not relock the bootloader unless you also flash the stock bootloader and lock it, which is not part of this guide.

Troubleshooting

Odin does not recognize the phone. Reinstall the Samsung USB drivers, try a different USB cable (the original cable is best), and ensure the phone is in Download Mode (not just connected normally). Check Windows Device Manager for any devices with a yellow exclamation mark.

Odin fails with “FAIL!” or “SW REV CHECK FAIL”. This usually means the firmware version you are flashing is older than what was previously on the phone. Download a newer firmware build for the SM-G850M. It can also mean you selected the wrong file in the AP slot.

The phone is stuck in a bootloop. Boot back into Download Mode (Volume Down + Home + Power) and reflash the same firmware. If it still loops, try a different firmware version, or wipe the cache partition from recovery mode (Volume Up + Home + Power, then select “Wipe cache partition”).

The phone shows “Custom binary blocked by FRP lock”. This means the OEM unlock was not enabled before flashing. You must boot the phone, go to Developer Options, enable “OEM unlocking”, then repeat the flashing process. If you cannot boot, you may need to use a service tool or contact a repair shop.

Odin flashes successfully but root is still present. Verify that the firmware you flashed is actually the stock Samsung firmware and not a pre-rooted custom ROM. Also, check that Odin completed with a green PASS and not a yellow “RESET” (which means it timed out).

Frequently Asked Questions

Will unrooting wipe my data? Yes, flashing stock firmware with Odin performs a full factory reset, erasing all apps, photos, messages, and settings. Back up everything before starting.

Does unrooting void my warranty? Unrooting restores the phone to a state indistinguishable from factory, so the warranty is effectively reinstated. However, the act of rooting itself may have voided it originally, and Samsung can sometimes detect the flash counter if it was not reset. This guide does not cover resetting the flash counter.

Can I unroot without a PC? No. The safest and most reliable method for the SM-G850M requires Odin on a Windows PC. Mobile apps that claim to unroot only remove the SuperSU app, not the modified system partition, which is not a true unroot.

Will I lose my photos and contacts? Yes, everything on the internal storage is erased. Photos on an external SD card are not affected, but contacts stored on the phone are. Sync contacts to Google before flashing.

Do I need to unroot to receive OTA updates? Yes. Official over-the-air updates will fail or cause a bootloop on a rooted device. Unrooting restores the stock system partition, allowing updates to install normally.

What if I flashed the wrong firmware and the phone is now bricked? If the phone still turns on and shows the Samsung logo, you can usually recover by booting into Download Mode and flashing the correct firmware. If it is completely unresponsive (no screen, no vibration), it may be a hard brick that requires a JTAG service or motherboard replacement.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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