And many main features such as Wi-Fi, Bluetooth, RIL, GPS, camera, audio, FM radio work as usual and it's less bugs, therefore this ROM is safe to be your daily driver. However be sure your Galaxy S4 Mini variant is supported (See the first paragraph) or else you might end up bricking your phone if you forcefully flash this ROM.
If you want to give this ROM a try, then this post will guide you to the entire process in installing the CM12.1 Android 5.1 ROM to your Samsung Galaxy S4 Mini. Be sure you prepare everything necessary before beginning, like making backups to your precious data like SMS, contacts, photos, app, etc. Do not think of messing with your phone without having backups.
- Be sure your Samsung Galaxy S4 Mini has bootloader unlocked, or else you won't be able to flash this ROM. At the same unlocking bootloader will nullify your warranty.
- Remember that you need to have either CWM or TWRP recovery installed for flashing the zip files of the ROM.
- And have a rooted Samsung Galaxy S4 Mini.
- Enable USB Debugging mode first.
- A computer with a USB cable.
- Have enough batter power now.
How to install Android 5.1.1 Lollipop on Samsung Galaxy S4 Mini using unofficial CM12.1 ROM
- Now download the CM12.1 Android 5.1.1 Lollipop for your Samsung Galaxy S4 Mini from this link and keep it on your computer.
- Download Gapps too, this ROM doesn't include Google apps thus we need to download and install separately.
- Now connect your Samsung Galaxy S4 to computer with the help of a USB cable. Transfer both CM12.1 ROM and Gapps files to your phone root directory within your internal memory.
- You can disconnect your phone from PC now and then it's time to enter to the recovery mode. Press Volume UP + Home + Power together.
- When you are within the recovery mode, you need to perform these actions.
Wipe data / factory reset.
The above three actions needed to clean the flashing process. Repeat the process each time you flash another custom ROM or upgrading it to newer version.
- Now you can go back to recovery main menu to choose ‘Install zip from SD card’ then browse to Unofficial CM 12.1 ROM ZIP file from your phone root directory.
- The installation process will begin, once it's done, you can simply Reboot System Now to reboot your phone.
Repeat the step 6 to 7 to flash Google apps.