How to Install Custom ROM on Realme C20 [GSI build]

In this tutorial, we will guide you to install the custom ROM on Realme C20. The device came out of the box with Android 10. If you want a vanilla-flavored custom ROM, then you can try the GSI build on your phone.

Well, If you are here, then you may probably want to install the Custom ROM on Realme C20. As you read our title, yes we can guide you on installing the latest custom ROM on Realme C20 based on GSI build.

When you buy a new phone, it comes with so-called stock ROM or stock firmware which basically means a pre-installed operating system. This ROM usually comes with some limited functionality defined by the OEM (phone manufacturer). Whereas a custom ROM is developed by using AOSP also known as Android Open Source Project. Yes, we all know that Android is open-source and therefore any developer can edit the code, or recompile it according to his or her need. You can read our complete article to understand the difference between Custom ROM and Stock ROM.

Flashing the ROM in Realme C20 is easy! All you need to do is follow the instructions carefully. If you are a newbie, then you need to understand that before flashing, you must unlock the bootloader on your Realme C20. To unlock the bootloader, follow our guide on how to unlock the bootloader on any Realme on any Android device.

If you already unlocked the bootloader, then you can simply follow our guide to install the custom ROM on Realme C20. Before that, let’s understand What is a GSI build.

What is GSI Stands for?

GSI stands for Generic system image which is an Android System image that can be used to replace the current installed Android version with a new one. It is a pure Android with an unmodified Android Open Source Project (AOSP) code. With Android 8.1, Google introduced the project treble support for many devices and now with Android 9.0 Pie, Google finally added the API level 28 to support Generic System Images to all app developers to install and run the latest Android GSIs on a variety of existing Android devices. To know more: Read here

How to Install Custom ROM on Realme C20

To install, as we said, you need to unlock the bootloader and must have a TWRP (to install via a  device) or a PC (to install via Fastboot). Yes, there are two methods to install the custom ROM GSI on Realme C20.

Pre-Requirements:

• This guide is for Realme C20.
• You will require to unlock the device bootloader at first
• ARM, ARM64, or x86: Check your Android Phone’s Processor
• Treble Support: Check If Your Smartphone Supports Project Treble
• Download the required file and Supported the GApps file from below.
• Keep your device battery charged up to 60% at least for a smoother process.
• Take a complete backup of your device data without Root. In case anything goes wrong, you can easily restore all the data.
• Download and install Realme USB Drivers
• For adb method: Download ADB and Fastboot tool
• For TWRP Method: Download and Install TWRP Recovery on Realme C20

Download Links:

• AOSP Quack Phh-Treble: Download
• LineageOS 18.1 Download – If broken link, check official forum

Install via TWRP Recovery:

This guide is for those users who have installed TWRP recovery on your device. If your device is not supported, you can try the next method to install the custom ROM via GSI build.

1. To install via TWRP, you need to factory reset your device using TWRP
2. Go into the Wipe option and Swipe to Factory Reset.
3. Transfer the GSI build to your Realme C20 using a USB Cable.
4. Once you have moved, you can remove your USB cable.
5. In your TWRP, tap on the install button –> Change type to Install Image and find the GSI you have moved in the 3rd step.
6. Confirm the flash by choosing the system partition
7. Once it is done, you can reboot your device and wait for a few minutes to boot up.

Flash via Fastboot

1. First, do the factory reset on Realme C20. There are two methods to do it, follow anyone.
   • Factory Reset When Powered On: To install without TWRP, you have to factory reset using your Umdigi A7 Pro factory reset option.
   • Factory Reset via Stock Recovery: Reboot your Realme C20 into stock recovery using a button combination or ADB command.

     adb reboot recovery

   • In your Stock Recovery, navigate using the Volume UP and DOWN button.
2. Make sure to extract the downloaded GSI build.
3. After resetting the factory ROM, you can now boot your device into bootloader mode using adb command adb reboot bootloader.
4. Now open the extracted folder of GSI build, there, now open the command prompt window by holding the SHIFT KEY and Right Mouse click.
5. In your command window, enter the command fastboot erase system
6. To flash the system image, enter a command in the following format: fastboot -u flash system name_of_system.img
7. Wait for the image to flash, it could take a few minutes. Once it has been completed, reboot your device either manually via power key or by entering fastboot reboot and wait for a few minutes to boot up.

We hope that this guide is helpful to you and you have successfully installed the Custom ROM on your Realme C20 handset easily. If in case anything goes wrong or if you have any queries, feel free to ask in the comments below.

Credits to all the developer from XDA forum and 4PDA forum