Samsung's first generation Galaxy S smartphone bearing model number GT-I9000 was first shipped with Android Eclair software and was later upgraded to Gingerbread version.

Samsung Galaxy S
The Galaxy S runs on Android 2.3 Gingerbread software version.

Galaxy S users, who have rooted their devices to experience the Ice Cream Sandwich (ICS) or Jelly Bean software and have consequently lost manufacturer's warranty, will be now able to reclaim the warranty by unrooting the same.

Galaxy S users, who wish to unroot their devices and return to stock official firmware, may follow our step-by-step guide.

IBTimes UK reminds its readers that it will not be held responsible for any damage to the device. Users are also advised to ensure that their devices meet following requirements.       

Pre-requites

1) Install USB Driver for Samsung Galaxy S to transfer files between the Android device and computer.

2) Enable USB Debugging Mode on the phone to connect the Android device with the computer and use the Android SDK with it. [Press Menu>> Settings>> Applications. From there navigate to Development option and now check for the USB Debugging.]  

3) As the tutorial might wipe all data of the phone, create a back-up. If the device is having any custom recoveries such as CWM/TWRP already installed then backup data using the recovery.      

4) The Galaxy S should have above 80 per cent of battery charge.

5) The phone should be factory unlocked and not locked to a particular carrier.

6) The Galaxy S should be rooted.

7) The official firmware works only on Samsung Galaxy S GT-I9000. Applying this on any incorrect variant might brick the device. Therefore, verify the model number of the Galaxy device by selecting Settings>> About Phone>> Model number.    

Steps to unroot Samsung Galaxy S GT-I9000 to stock official firmware

Step-1: Download appropriate (according to region) official firmware for Samsung Galaxy S to the computer

Firmware download link

Step-2: Extract the downloaded firmware zip to get a .tar.md5 file along with few other files   

Step-3: Download Odin3 v1.85 which will help to install the official firmware. Extract the Odin zip 

Step-4: Switch off the Galaxy S

Step-5: Now boot the phone into Download Mode by pressing and holding Volume Down, Home and Power buttons together. Now press the Volume Up button to continue to enter into Download Mode   

Step-6: Now run Odin by double clicking the Odin executable file

Step-7:  Plug in the USB cable to the phone to connect it with the computer while the device is in the Download Mode.  Wait until Odin recognises the phone. Once the device is connected successfully an Added message will appear under Odin. Also the successful connection will be indicated by the ID: COM turning yellow with the COM port number

Note: If the Added message does not come then try another USB port, try the one located at the back side of the computer. If Odin still fails to recognise the device then reinstall USB driver.

Step-8: Now select these files extracted from the firmware zip folder to install on the phone

a) Click the PDA button and select the file with .tar.md5 extension

b) Click the Phone button and select file with Modem in its name

c) Click the CSC button and select file with CSC in its name

d) Click the PIT button and select the .pit file 

Note: Ignore the last three steps (b, c and d) if such files are not found.

Step-9: Verify that the Auto Reboot and F.Reset Time checkboxes are selected in Odin. But uncheck the Re-partition option, select it only when a .pit file is being used

Step-10: Now click the Start button in Odin. The installation should begin now and would take few minutes to complete

Step-11: Once the installation process is completed, the phone will restart automatically. When the home screen appears on the phone, unplug the USB cable from the device to disconnect it from the computer

Samsung Galaxy S should be unrooted now and running on stock official build. Navigate to Settings>> About phone to verify the software version of the device.

Also read: Install Android 4.3 on Galaxy S I9000 via CyanogenMod 10.2 unofficial build [GUIDE]

[Source: The Unlockr]