Install Android 5.1 on S2

Recently I found a Samsung Galaxy S2, it was running on old Android Jelly Bean. I thought I should try to install Android 5.1 on S2. Did some research and in the end, I was successful in installing Android 5.1.1 on it using CyanogenMod 12.1. So here is a guide for you guys as well.

Update: This guide no longer works to install Android 5.1. I have updated it to install Android 7 using LineageOS 14.1.

General opinion is that the phone will get slow after getting the new operating system. But few people know that the latest operating system has better apps optimization, it is efficient and it can do stuff consuming very little processing power. After updating to Android 5.1.1. I noticed great performance boost in S2, and it was running a lot more faster than Android 4.1.2. Now let’s move on to the guide on how to install Android 5.1 on S2. I have used CyanogenMOD 12.1 which is a stable version to get Android 5.1 on S2.

In order to get Android 5.1 cyanogenMOD 12.1 on your S2, you will first have to root your phone and then you will have to flash the firmware and the lastly you will have to install the Google apps. I have covered each part in the guide below.


  • Download LineageOS 14.1 Android 5.1 stable firmware file from here. (Click on Download through Browser).
  • Download Samsung Drivers for Windows. (Link to download file is under the main heading)These drivers are to be installed on your PC, they are essential for your PC to recognise your device properly.
  • Download ODIN from the official site of ODIN. Or you can download the ODIN I used from this link.
  • Download ClockWorkMod Recovery from here. Use the blue button to download the file.
  • Download Gapps (Google Apps) from here. As this guide is for S2 and we are installing Android 5.1 so select ARM, Android 5.1 and in the third column select whichever seems suitable for you. I selected nano version.
  • Download SuperSU Rooting Zip file.

How to Install Android 5.1 on S2 [CyanogenMod 12.1]

  1. First of all download the CyanogenMod 12.1 that is AOSP of Android 5.1, Gapps and SuperSU rooting file from above links and move them to your phone. You can place them in internal storage (Recommended) or external SD card. ( I have placed them in external SD card thats why I selected choose zip from SDcard)
  2. Once you have downloaded and moved the files in your phone now you have to install custom recovery on your phone. Use this guide on how to flash ClockWorkMOD custom recovery on your S2.
  3. After you have installed custom recovery. Turn off your phone and go to custom recovery. Press Volume up, Home and power button simultaneously for long time till you boot into custom recovery. First you will notice Samsung logo flash couple of times and you will see yellow sign under it. Don’t worry about it. Keep on holding the buttons till you see the custom recovery menu.
  4. Now you have to flash the SuperSu file to root your phone. For that to go install from sdcard -> Choose zip from sdcard – > Now Select the CWM file. Let it flash. See the screenshot below.
  5. Install Android 5.1 on S2Now you have to install Android 5.1 on S2. Steps are same as above Goto Install from Sdcard -> Choose zip from Sdcard -> Select CM file. It will take some time to flash.
  6. Now you have to install Gapps. Steps are same as above Goto: Install from SDcard -> Choose zip from SDcard -> Select Gapps.
  7. Now just few steps left. Go back to recovery menu and select wipe data/factory reset.
  8. After that select the option “Clear cache partition“.
  9. Now in recovery menu goto: Advanced -> Select Wipe Dalvik Cache.
  10. Now Go back to recovery menu and select reboot system now.

That’s it, Now your phone will reboot and It will have Android 5.1

Install Android 5.1 on S2

If you have any issue regarding how to install Android 5.1 on S2 using cyanogenMOD let me know in the comments. You can also drop feedback in the comments. If you have any query feel free to ask us. Rooting and installing custom ROMS can sometimes lead to some issues, so if you come across any issue while performing how to instal android 5.1 on s2. Dont freak out, ask me in the comments, I’ll get back to you as soon as possible.


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