How to install Lollipop-based CyanogenMod 12 on the Galaxy S2 (I9100)

The Samsung Galaxy S2 was released on February 13th, 2011, and was the predecessor of the first Android device to truly rival the iPhone in both sales and popularity. Four years is almost an eternity in the world of tech, but that hasn’t stopped the XDA Developers community of finding a way of getting a stable Android Lollipop build up and running on the Galaxy S2.

The build was posted by XDA user Lysergic Acid, and is a pure, yet unofficial Cyanogenmod 12 build. From what I have read in the thread, the newest version of the build seems fairly stable, but still has some issues with HD video recording and for some some internal storage bugs. This is a 5.0.2 Lollipop release, so there won’t be any signs of Touchwiz here. This particular build is for the I9100 only and does require root. Make sure you are flashing this ROM on the correct device before you get started.

As with most builds on XDA, you will need to root your device. I have rooted the S2 a million times, and although very simple to do, here’s the standard disclaimer: You root at your own risk. If you brick your device, Android Authority or XDA Developers are not responsible. You are in essence voiding your warranty, meaning Samsung can deny you service should they choose to.

Now if you decide you want to try it out, you can root your device (literally in minutes by following the simple step by step instructions here via Chainfire’s CF Root method). Once you have root, you’ll need a KitKat compatible custom recovery to flash the ROM.

Once you have root, do the following:

1. MAKE A NANDROID BACKUP!
2. Download the ROM and the Google Apps package from the XDA thread here and put it on your sd card.
3. Boot into recovery and wipe all data.
4. Flash the ROM.
5. Flash the Gaaps package.
6. Reboot your phone, and remember the first boot can take a little longer than usual.
7. Profit.

If you want to see it running before flashing it, XDA member @Troubadour666 put together this video that shows the ROM running on the S2:

I imagine it was no easy feat getting CM12 to run on a four year old device (and especially this well), so be sure to hit that thanks button to everyone responsible if you choose to flash the ROM. While it’s not realistic to expect Lollipop to be as fast and smooth as it is on most (but not all) newer devices, having a stable daily driver in Lollipop will most likely excite a few S2 users out there. Be sure to let us know in the comments how it’s running on your Galaxy S2.