This post will also explained how to install Lineage OS Marshmallow based to Xiaomi Redmi 4 Prime and show you what are need to be prepared before flashing this custom rom into Xiaomi Redmi 4 Prime markw devices. And please read with carefully the instalation guide below.
Important to note:
• This tutorial only supported the Xiaomi Redmi 4 Prime devices, codenamed with (markw). Dont use this rom to another Xiaomi devices.
• Make sure your Xiaomi Redmi 4 Prime bootloader unlocked and have a TWRP Recovery installed. Read this guide to unlock bootloader xiaomi devices and this guide to install twrp recovery.
• In order to install correctly this Custom ROM you will need to wipe the data and/or factory reset your Xiaomi Redmi 4 Prime. This step is included in the tutorial and it means that you will have to backup all your files using cloud storage services (mi cloud is good but using google drive much easier to restore), a SD Card or a PC. Using Titanium Backup is not recomended.
Please Create a nandroid back-up to anticipate if something bad happened during intstalation or after instalation. So you can restore to the earlier rom you used with nandroid backup you'll created.
• Make sure that your smartphone’s battery charge level is over 20% or more, at least 60% is good enough. This will prevent it from powering down while you’re updating your Redmi 4 Prime (markw) to Marshmallow 6.0 using Lineage OS ROM
If you done with all prequisites mentioned above, you can now forward to these steps by step guide.
1. Download ROM LineageOS 13.0 Xiaomi Redmi 4 PrimeThis release is unofficially released rom. This Unofficial LOS 13.0 is on beta stage, surely you can leave this page if you don't interested. Offcourse, it will (probably) have some issues after you install this build. If you insist after knowing this, download LOS 13 for Redmi 4 Prime below, and don't blame us if something bad happened:
2. Download Marshmallow Lineage OS GappsLineage OS 13.0 ROM is commonly based on Android 6.0 with 64 bit architecture, you can download these smallest compatibel GApps package with arm64 arch and sdk 6.0, provided by opengapps.org below
Pico Gapps Marshmallow Lineage OS
Those above is the smallest package and Aroma variant is the argest package with instalation wizard powered with Aroma Installer. If want more option go ahed choose suitable gapps marshmallow package according your data plan.
3. Installing Nougat 6.0 Lineage OS on Xiaomi Redmi 4 Prime
How to Install Marshmallow Lineage OS on Xiaomi Redmi 4 Prime (markw) and adding GApps into Lineage OS:
• Transfer both the Custom ROM and Marshmallow Lineage OS Gapps packages to the internal storage of your device.
• Power off your device and boot into TWRP Recovery mode. Once, you are into TWRP Recovery main menu, you need to make a hard reset. From the TWRP main menu tap on the wipe button and select Advanced Wipe. Then select all Dalvik cache, System, Data and Cache options.
• Flash the custom ROM now. Choose the Install option from the recovery menu and choose the ROM zip from the file manager.
And while you waiting, you can have some popcorn 😀
• Reboot into revovery after completed, don't reboot into system yet.
• Now, flash the Nougat Lineage OS Gapps package that you’ve downloaded before in the same way as you did with the custom ROM
Reboot the device into system and complete the initial setup. Enjoy Android Nougat 7.1 with Lineage 13.0 for Xiaomi Redmi 4 Prime
Now you know where you can download Marshmallow 6.0 Lineage OS Unofficial ROM for Redmi 4 Prime (markw) and how to install it on your smartphone.
You can also read how to enable native root access in Lineage OS.
In that guide also explain to you how to replace native root with SuperSU without flashing zip.
Please leave your review in the comment section. Or if you have problem, don't hesitate to write a question in the comment section of LineageOS 13.0 for Xiaomi Redmi 4 Prime Android MM 6.0
 XDA Forum link