Both devices are very old, as the Galaxy S3 was released in 2012 and the Note 3 phablet arrived a year later. Normally, every manufacturer is committed to a full two years of upgrades and after that, the owners need to find a way to get the newer Android versions. The good news is that individual developers are releasing custom ROMs especially for specific smartphones and the owners of the aforementioned devices are now able to install Lollipop update through two different ROMs.
So, the owners of the Note 3 phablet can install Android 5.1.1 Lollipop FlymeOS Custom ROM, which is very stable and provides a smooth performance. This ROM has been developed especially for the LTE version of the Note 3 (N9005), a phone that came loaded with Android 4.3 Jelly Bean and it was upgraded to Android 4.4.2 KitKat in the meantime.
Since the phablet will not get the latest Marshmallow update, at least there is a CyanogenMod stock-based Android 5.1.1 Lollipop update available for it and FlymeOS ROM brings Flyme Camera as its most important feature, alongside SPEN features and the rest of Google applications. The users will get support for custom font and custom DPI and they will surf freely on the internet without seeing ads, thanks to Adblocker.
Those who will device to install this unofficial Android 5.1.1 Lollipop update, must root their devices and create a backup of all the data and settings using a desktop tool called Samsung KIES. They will also need a custom recovery tool and we recommend ClockWorkMod. Before starting the installation of the custom ROM, the users will make sure that the battery has at least 80 percent left of juice, otherwise the phone will shut down before the installation completes and the device will be bricked. The Note 3 will be connected to a computer using a USB cable, but not before USB Debugging mode will enabled.
The most popular custom ROMs available for the Note 3 are CyanogenMod ROM, Darklord, Aurora, SmokkieROM and Phronesis.
The Galaxy S3 owners are also spoiled with an Android 5.0 Lollipop custom ROM, but they will need to get the arter 97 kernel as well. The custom ROM file will be downloaded both for the phone and desktop, then the users will unzip the arter 97 kernel file, connect the phone to the PC and perform a Nandroid back up (the file will be put in /sdcard/clockworkmod/backup). After that, the phone will be disconnected from the PC and it will be restarted and booted into recover mode. After that, the users will select “wipe data factory reset”, “wipe cache partition” and “wipe dalvick cache”, then they choose the “Backup and Restore” option and after restoring backup, they will the arter 97 kernel (“install zip from SD card”) and select “choose zip from SD card”.