Possibly one of the most popular custom ROMs based on the very latest Android 5.1 Lollipop is Resurrection Remix. Based on CM12, you will get all the loveliness of Lollipop with CyanogenMod features on top. Here is how you can flash Android 5.1 on Galaxy S4 I9500 with Resurrection Remix.

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Resurrection Remix Android 5.1 features:

Navigation BarStatusbarBrightness SliderEnable/Disable Show Notification CountClock CustomizationsTime & dateBatteryBattery Bar customizationBattery Icon Customization(circle/landscape/Potrait and more)AnimationsGestures Anywhere FeatureClock WidgetLockScreenLockscreen ShortcutsNotification DrawerQuick SettingsBacklight TimerHome Button(For devices with HW keys Only)Home Button Wake UpHome Button answer callLCD DensityExpanded Desktop ModeAll New CM Audio FX AppHeads Up CustomizationsOverAll Smoothness ImprovementsQuick UnlockOptimizations to Improve BatteryALL CM12 featuresand many many more...

Prerequisites to flash Android 5.1 on Galaxy S4 I9500 Resurrection Remix:

Backup any important datafrom your Samsung Galaxy S4 I9500 as a complete wipe will be required during the flashing process.Enable USB debugging option on your device:Settings>DevelopmentOptions>USB debugging.Samsung Galaxy S4 I9500 must berooted, unlocked and installed with a recovery tool likeTWRPorCWM.Your device must be charged to at least 60% of power.

Note:this tutorial is focused on Samsung Galaxy S4 i9500; kindly do not try this guide on otherAndroid&Samsungdevices.

How to flash Android 5.1 on Galaxy S4 I9500 with Resurrection Remix ROM:

Required files: downloadthe Android 5.1 Lollipop custom firmware for Galaxy S4 fromhereand save it on your computer. Do not extract the contents. Also download Google Apps Package.

Connect yourGalaxyS4 to your computer using a USB cable and copy the zip file to your phone’s SD card.Disconnect the USB cord andpower off your Galaxy S4.Boot it into recovery mode: switch the phone on while pressing and holding Volume Up + Home + Power buttonssimultaneously.Perform aNandroid backupof your current OS:Backup>backup and restoreon ClockworkMod recovery.Wipe data task: from CWM recovery menu, selectwipe data / factory resetand confirm the process.From recovery menu, selectinstall zip from sdcardfollowed bychoose zip from sdcard.Locate the Resurrection RemixAndroid 5.1 Lollipopcustom firmware and confirm the flashing process.Return back to main recovery menu and reboot yourGalaxyS4 I9500into the new custom ROM. First boot takes a good 5 minutes so please be patient.