How to Install Custom ROM on Samsung Galaxy A51 [GSI build]

If you already unlocked the bootloader, then you can simply follow our guide to install the custom ROM on Samsung Galaxy A51. Before that, let’s understand What is a GSI build.

Samsung Galaxy A51 Device Overview:

The Samsung Galaxy A51 sports a 6.5-inch FHD+ Super AMOLED Infinity-O display with an aspect ratio of 20:9. The display also has an 87.4% screen-to-body ratio and a pixel density of 405 PPI. The display also contains the in-display fingerprint scanner and Corning Gorilla Glass 3 protects the device. The device has a plastic back and the same plastic frame too.

Underneath the device, the in-house octa-core Exynos 9611 SoC which pairs Mali-G72 MP3 powers the Galaxy A51. This SoC is built on the 10nm process and this also pairs with 6 and 8GB of RAM and 64 and 128GB of internal storage. Further, the storage is expandable via a MicroSD card up to 512GB. The device has a dedicated SIM slot where at a time you can insert two nano SIM’s and a micro SD card.

Talking about optics, the Galaxy A51 has a quad rear camera set up in an L-shaped arrangement. This quad-camera setup includes a primary 48MP sensor with an f/2.0 aperture value. This sensor pairs with a 5MP secondary depth sensor with an f/2.2 aperture. Further, it also sports a 5MP tertiary macro sensor with an f/2.4 aperture value. Finally, the device also sports a 12MP ultra-wide camera with an f/2.2 aperture value. To the front, the device sports a 32MP sensor with an f/2.2 aperture value.

The Galaxy A51 packs a 4000 mAh battery which supports up to 15W quick charge and also charges over type c. The device runs one One UI 2.0 which is based on the latest Android 10. It is available in four colors namely the Prism Crush Black, White, Blue, Pink. Connectivity options include Wi-Fi 802.11 a/b/g/n/ac, dual-band, Wi-Fi Direct, hotspot, Bluetooth 5.0, A2DP, LE, GPS with A-GPS, GLONASS, GALILEO, BDS. It has also support for NFC on board.

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 Samsung Galaxy A51

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 Samsung Galaxy A51.

Pre-Requirements:

• This guide is for the Samsung Galaxy A51.
• 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 Support 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 Xiaomi USB Drivers
• For adb method: Download ADB and Fastboot tool
• For TWRP Method: Download and Install TWRP Recovery on Samsung Galaxy A51

Download Links:

• Download AOSP Android 12 GSI
• AOSP 11.0 Quack Phh-Treble: Download
• HAVOC OS 4.1 GSI: 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 Samsung Galaxy A51 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 the Samsung Galaxy A51. 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 Samsung Galaxy A51 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 the 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 Samsung Galaxy A51 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 developers from the XDA forum and 4PDA forum