Hi 🙂 Here, I  am sharing my experiences on flashing a custom firmware on  my Samsung Galaxy S4 GT-19500 device including the installation of Open Gapps packages. Currently, I have the Official Firmware Lolipop 5.0.1 on my device. The custom firmware I’m going to flash is the Android 6.0.1 CM13 which I obtained from the website https://www.teamandroid.com/roms/ .

(Warning: This approach works only for this particular Android device. As always warned by XDA developers, trying out it is all under your own responsibility. Your device may be bricked if things didn’t go well.)

Step 1: Root the device.

First, you have to root the device using KingRoot.apk.

• Download the KingRoot.apk to the device (You can search it for online; an blue icon with a crown).
• Enable “Unknown Sources” in the Settings, to allow installing the apk. You may still get “Bolcked by Play Protect” popup message. Press “Install anyway” at the bottom line of that message to continue installing.

Step 2: Install an Odin enabled TWRP recovery on the device.

• Download the zip file (an odin enabled TWRP for Galaxy s4 GT-19500 by teamwin): samsung-galaxy-s4-i9500-twrp-odin .zip
• You need an Odin software to flash the zip file. I used Odin3 v3.13.1 software (downloaded from https://odindownloader.com/). Select the zip file under “AP” and Press Start.

Note*: Please refer to the Steps 2-6 in my previous post to install the recovery zip file using Odin without trouble.

Step 3: Obtain the Android 6.0.1 CM13 Custome Firmware.

• Download the cm-13.0-20160101-UNOFFICIAL-GearCM-i9500.zip from your Samsung Galaxy S4 device. The file will be stored at /storage/emulated/0/Downloads.

Step 4: Prepare the device for the Installation.

• Turn Off the device. Press buttons (Volume Up+Power+Home) to obtain the “Recovery Mode”. You will get the teamwin screen and the menu followed by that.

• First Select “Backup” and backup all your data and system.
• Next Select “Wipe” –> In the “Factory Reset” page Swipe to perform the wipe of data, cache and dalvik.

• After that, Select “Install” –> Select the custom firmware zip file from the list of files –> Swipe to confirm flash.

• Finally, once  the zip file installation is completed, select reboot system.
• If the installtion was successfull, after the reboot the you will get the Cyangenmod Welcome page. Continue… the settings.

• Verify the installation by viewing “about device” in the settings.

Step 5: Installing Gapps on your Marshmallow device

You will see that the newly installed Marshmallow doesn’t contain apps like Gmail, Play Store, Chrome etc,. This is because the cm13 custome firmware we installed does not contain the gapp packages. Therefore, we will have to download it from an online website through you PC.

• Download open_gapps-arm-6.0-nano-20190127 zip file.
• Next, use the adb to push the file to the device /storage/emulated/0/Download.

• After that, turn off the device –> Goto recovery mode —> Wipe the Cache –> install the zip file.

Note*: I tried to install the open_gapps_arm_6.0.stock version. However, there was a problem launching nexuslauncher package. Therefore, reflashed the Android 6.0.1 again and installed the nano version which was successfull. The nano version includes the google play app.

Cheers ! 🙂