[General Topics] IverCoder:
This guide is for Samsung Galaxy A03 only and assumes you have updated to the latest firmware. While it has been tested with SM-A035F, it may also work on SM-A035G and SM-A035M. Proceed at your own risk. Back up your files as all your data will be wiped in the process.​

Step 1: Download stock firmware​

Go to SamFw and enter your phone's model in the search bar, in my case SM-A035F for my Asian model. In the list that shows, select your CSC code. If you don't know it, you can see the three-letter combination under "Service provider SW ver." in Settings > About phone > Software information. Then select and download the latest version on the list.

Step 2: Preparing Magisk​

On your computer, download and install 7-Zip ZS.

Extract the firmware .zip file you downloaded earlier. Extract the AP file with 7-Zip and get the boot.img file. Send this file to your phone, preferably with a USB cable.

Back to your phone, download and install Magisk from the official GitHub releases. Do not download Magisk from anywhere else. Patch the boot.img file. Send the patch image back to your computer.

Rename the patched file back to boot.img and compress it into a .tar archive using 7-Zip.

Set aside the resulting .tar file for flashing later.

Step 3: Preparing Fastboot-patched recovery​

Follow the instructions on this GitHub repo. Extract the resulting .zip file and set aside the .tar.md5 file inside for flashing later.

Step 4: Download and install Odin and drivers to your computer​

Download this file. Extract it and just open the Odin executable inside.

Download and install Samsung USB drivers from the official Samsung website. Restart your computer after installation.

Step 5: Download and install SDK Platform Tools to your computer​

Download the SDK Platform Tools from the official Android website. Extract the downloaded .zip file. Take note of the platform-tools folder, which is the directory where fastboot is installed.

Step 6: Unlocking the bootloader​

Follow this section of the Magisk install guide. Follow the bootloader unlocking section only and ignore everything else on the page.

To open download mode on this device, plug in the phone to your computer while Odin is opened and long press the Volume+ and Volume- keys.

Step 7: Flashing Magisk and Fastboot recovery​

Open Odin on your computer and boot your phone to download mode.

Click the AP bar and select the patched Magisk .tar file from before.

On the Options tab, make sure that Auto Reboot is disabled. Click "Start" and wait for the flashing to finish.

Close Odin and open it again, then power off and boot your phone back to download mode again by holding down the Power and Volume- buttons for several seconds. When the screen goes black, immediately let go of the Power and Volume- buttons and press Volume+ and Volume- instead. It's fine to fail this step but it would be very inconvenient and time-wasting.

Follow steps 2 and 3 again but select the Fastboot-patched recovery .tar.md5 file instead.

You can now reboot to system if you don't intend to install a GSI. Or, reboot to recovery by holding down Power and Volume- for several seconds and immediately switching to Power and Volume+ if you want to flash a GSI now. Proceed to the next section in that case.

Step 8: Flashing a GSI​

ℹ️ If Fastboot on Windows has trouble detecting your phone, use Linux instead.

On your computer, move the GSI image to the folder where fastboot is installed and rename it to system.img. If the image is compressed (e.g. the filename ends with .xz), uncompress it first with 7-Zip.

If you are not yet in recovery, enter it now by powering off your phone and holding Power and Volume+.

Using the volume and power buttons, select Wipe data/factory reset and confirm the action.

Select Enter fastboot.

Open the folder where fastboot is installed on the terminal by right-clicking while the folder is opened and then pressing "Open in Terminal".

Run this command to flash the GSI:

./fastboot flash system system.img

You can now reboot to system.

If you can't receive incoming text messages, particularly on firmware A035FXXU4CWI1 and later, use this Magisk module to fix it.​

Tested GSIs​

PixelOS 14.0-20231114

VoltageOS 3.1-20240131

PixelOS 14.0-20240130

Use the LATEST version of these GSIs instead of the linked version for maximum stability.