- CM 12.1 Nightly ROM is based on AOSP thus you need to firstly unlock your device bootloader.
- It's not a final release, but still in Nightly stage, thereof things unwanted could happen like apps stop working, bootloop, and such. If that happens you can restore to the stock firmware.
- Enable your Android Galaxy Premier USB debugging mode.
- Already installed a custom recovery like CWM or TWRP.
- If your device is rooted, it would be better, however that's not really a requirement.
- Remember to firstly make backups over your data stored on your smartphone, you can backup your apps + data using Helium app, or AirDroid app to backup SMS, photo, contacts, music, etc.
- Apply this tutorial only if your smartphone is Samsung Galaxy Premier I9260.
Update Samsung Galaxy Premier I9260 To Android 5.1.1 Lollipop Using CM12.1 Nightly BuildFiles you need.
- Now connect your smartphone to your computer with the help of a USB cable.
- When they are successfully connected, then transfer all the zip files you downloaded previously to your smartphone internal storage (recommended to place the files into root folder).
- When all the files transferred to your phone's internal storage, you can disconnect your Samsung Galaxy Premier from USB cable.
- Now you can turn off your phone by selecting power off option, to further reboot into the recovery mode by pressing and holding Volume Up + Home + Power buttons simultaneously.
When you feel your phone vibrates, release the Power button only. Keep other buttons. When an Android green robot shows up release all the pressed buttons.
- Within the recovery you need to perform the series of cleaning. Firstly select Wipe Data/ Factory Reset option.
- When done with the above task, go back to further selecting Wipe Cache Partition. Now move to Advanced menu to choose Wipe Dalvik Cache. You need to also clean system and data partitions as well in this area.
- Now go back to the recovery main menu to further choosing the Install Zip From SD Card continue with selecting Choose Zip From SD Card option then get the CM12.1 Nightly Android 5.1.1 zip file you previously transferred to your phone's internal storage. The flashing process will then begin,
- Once done. You can continue to flash the Gapps zip file to get the Google official apps installed on your phone.
- When all the tasks completed, select the *****Go Back***** and then choose the Reboot System Now option to reboot your Samsung Galaxy Premier into a normal mode and load the ROM and the Gapps altogether. That would take a longer time than usual. Just wait guys.