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The Realme C21Y (model numbers RMX3261 and RMX3263) is a popular budget smartphone powered by the Unisoc T610 processor. While it offers solid performance for everyday use, many power users and Android enthusiasts want to go beyond what the stock software allows. Installing a custom recovery like TWRP (Team Win Recovery Project) is the essential first step toward unlocking your device's full potential,   enabling you to create full system backups, flash custom ROMs, root with Magisk, install modifications, and much more.

However, installing TWRP on the Realme C21Y can be tricky if you don't follow the correct procedure. Many users encounter the frustrating issue where TWRP gets automatically overwritten by the stock recovery after the first system boot. This happens because modern Android systems include a security feature that restores the original recovery partition on boot.

This guide is specifically designed to be fail-proof. We'll walk you through every step from preparing your device and unlocking the bootloader to flashing TWRP correctly and performing the critical post-flash procedure that ensures TWRP stays installed permanently. By following these instructions carefully, you'll have a working, permanent TWRP recovery on your Realme C21Y without bootloops or recovery overwrites.

⚠️ Important Warnings Before You Begin

1. Data Loss: Unlocking the bootloader will perform a factory reset, erasing all your personal data. Back up everything important photos, videos, contacts, app data before proceeding.
2. Warranty Void: Unlocking the bootloader and installing custom software will likely void your official Realme warranty.
3. Risk of Bricking: While the methods in this guide are well-tested, any mistake during the procedure could potentially render your device unbootable. Follow every step precisely.
4. Model Compatibility: This guide is specifically for the Realme C21Y (RMX3261, RMX3263). Do NOT attempt this on other Realme models, as it may cause serious issues.
5. Battery Level: Ensure your device has at least 70% battery charge before starting to prevent unexpected shutdowns during the process.

✅ Prerequisites

Before starting the TWRP installation, ensure you have all of the following:

Item Description Realme C21Y Model RMX3261 or RMX3263, fully charged Windows Computer Windows 7, 8, 10, or 11 USB Type-C Data Cable Original or high-quality charge-only cables will NOT work ADB & Fastboot Tools Android Platform Tools installed on your computer Realme USB Drivers Properly installed for device detection TWRP Image File Correct TWRP .img file built specifically for Realme C21Y Internet Connection Required for the bootloader unlock application process Complete Backup All personal data backed up to external storage or cloud

Step 0: Unlock the Bootloader (MANDATORY)

You cannot install TWRP on a device with a locked bootloader. Realme requires users to apply for bootloader unlock permission through their official process.

How to Unlock Realme C21Y Bootloader:

1. Enable Developer Options:
   • Go to Settings → About Phone
   • Tap Build Number 7 times until you see "You are now a developer"
2. Enable USB Debugging & OEM Unlocking:
   • Go to Settings → Additional Settings → Developer Options
   • Toggle USB Debugging to ON
   • Toggle OEM Unlocking to ON and confirm
3. Apply for Deep Testing:
   • Download and install the official Realme Deep Testing App from the Realme community website
   • Open the app, apply for "Deep Testing" access, and wait for approval (usually takes a few minutes)
   • Once approved, tap "Start deep testing" your device will reboot into Fastboot mode
4. Execute Unlock Command:
   • Connect your device to the computer via USB
   • Open Command Prompt or Terminal in your ADB/Fastboot folder
   • Type the following command and press Enter: plaintext

     fastboot flashing unlock
     

   • On your phone screen, use the Volume keys to select "Unlock the bootloader" and press the Power button to confirm
   • The device will automatically perform a factory reset and reboot

⚠️ This step erases ALL data on your device. After the reboot, go through the initial setup, re-enable Developer Options and USB Debugging before proceeding to the next stage.

Step-by-Step: Install TWRP Recovery on Realme C21Y

Step 1: Prepare the TWRP Image File

1. Download the correct TWRP recovery image file (.img format) specifically built for the Realme C21Y (RMX3261/RMX3263).
2. Rename the downloaded file to something simple, like twrp.img for easier command typing.
3. Place the twrp.img file into your ADB & Fastboot tools folder on your computer the same folder where fastboot.exe is located.

Step 2: Boot Your Realme C21Y into Fastboot Mode

There are two methods to enter Fastboot mode:

Method A:   Using ADB Command (Recommended):

1. Connect your device to the computer via USB
2. Open Command Prompt in your ADB folder
3. Type: plaintext

   adb devices
   

   • If prompted on your phone to "Allow USB debugging," check "Always allow" and tap OK
   • You should see your device serial number listed
4. Now type: plaintext

   adb reboot bootloader
   

5. Your device will reboot into Fastboot mode

Method B:   Using Hardware Keys:

1. Power off your Realme C21Y completely
2. Press and hold the Volume Up button + Power button simultaneously
3. Keep holding both buttons until you see the Fastboot mode screen
4. Connect the device to your computer via USB

Step 3: Verify Fastboot Connection

1. In the Command Prompt window, type: plaintext

   fastboot devices
   

2. You should see your device serial number appear. If nothing appears:
   • Reinstall Realme USB drivers
   • Try a different USB port (preferably a rear USB 2.0 port on the motherboard)
   • Try a different USB data cable

Step 4: Flash TWRP Recovery Image

1. With your device in Fastboot mode and connected, type the following command: plaintext

   fastboot flash recovery twrp.img
   
   

2. Press Enter. You will see progress messages indicating the flashing process.
3. When successful, you'll see a message like "OKAY [ X.XXXs] Finished."

Step 5: THE CRITICAL "ANTI-GAGAL" STEP:   Boot DIRECTLY to TWRP

This is the most important step in the entire guide. If you skip this or do it incorrectly, TWRP will be overwritten by the stock recovery, and you'll have to start over.

DO NOT use the command fastboot reboot and DO NOT let the device boot normally into the Android system. Instead:

Option A:   Using Fastboot Command (Most Reliable):

Immediately after the flash completes successfully, type this command:

plaintext

fastboot reboot recovery

Option B:   Using Hardware Keys:

If the command above doesn't work on your device variant:

1. As soon as the screen goes black after the flash, press and hold Volume Up + Power
2. Keep holding both buttons continuously;   do NOT release them
3. The device will attempt to reboot; keep holding until you see the TWRP recovery screen

Why this works: Modern Android systems (including Realme UI) have a built-in mechanism that restores the stock recovery partition during the first normal system boot after a modification. By booting directly into TWRP first, we Unlock this mechanism and can then make TWRP permanent from within TWRP itself.

Step 6: Make TWRP Permanent from Within TWRP

Once you're successfully inside the TWRP recovery interface:

1. Allow Modifications: When TWRP first loads, it may ask "Keep system read-only?" Swipe the slider to allow modifications. This is essential for making TWRP permanent.
2. Format Data (If Encrypted):
   • If TWRP asks for a decryption password or cannot read your internal storage, go to Wipe → Format Data
   • Type "yes" to confirm and remove encryption
   • After formatting, go to Reboot → Recovery to restart TWRP with accessible storage
3. Flash TWRP Permanently (Method 1:   Flash Current TWRP):
   • In the TWRP main menu, go to Advanced
   • Look for an option called "Flash Current TWRP" or "Install Recovery Ramdisk"
   • Select it and swipe to confirm
   • This flashes the currently running TWRP image to the recovery partition from within the recovery environment itself, Unlocking the system's restore mechanism
4. Alternative: Use Multidisabler Zip (Method 2):
   • If your TWRP doesn't have the "Flash Current TWRP" option, you'll need the multidisabler.zip file
   • Copy the multidisabler.zip to your device's internal storage or SD card
   • In TWRP, go to Install, select the multidisabler.zip file, and swipe to flash
   • This zip disables the system's recovery restoration service, encryption, and vaultkeeper,   ensuring TWRP stays installed

Step 7: Reboot to Verify

1. After completing either Method 1 or Method 2 above, go to Reboot → System in TWRP
2. Let the device boot fully into Android
3. Once the system is up, power off the device completely
4. Now test whether TWRP is permanent: Press and hold Volume Up + Power to boot into recovery mode
5. If you see the TWRP interface instead of the stock Realme recovery,   CONGRATULATIONS! You have successfully installed permanent TWRP recovery on your Realme C21Y.

What Can You Do with TWRP?

Now that you have a working TWRP recovery, a world of customization opens up:

1. Create Full System Backups (NANDroid): Take complete snapshots of your entire system that you can restore anytime an essential safety net before making any modifications.
2. Flash Custom ROMs: Install custom Android versions like LineageOS, Pixel Experience, or other GSI builds for newer Android versions and better performance.
3. Root with Magisk: Flash the Magisk ZIP file to gain root access, enabling root-only apps, system modifications, and ad-blocking.
4. Install Mods & Tweaks: Flash various ZIP files that modify system behavior, improve battery life, enhance performance, or add features.
5. Selective Wiping: Instead of full factory resets, wipe specific partitions (cache, dalvik, system) when switching ROMs or troubleshooting.
6. File Management & Rescue: Access and manage files on your device even when the main Android system won't boot,   great for recovering data from a soft-bricked device.

Troubleshooting Common Issues

Issue 1: TWRP Gets Overwritten by Stock Recovery

• Cause: You booted to system directly after flashing instead of booting directly to TWRP first.
• Fix: Start over from Step 4 (flash TWRP again), then immediately perform Step 5 correctly:   boot directly to TWRP using fastboot reboot recovery or the hardware key method.

Issue 2: "fastboot boot" Command Not Recognized

• Cause: Some Realme devices with Unisoc chipsets do not support the fastboot boot command.
• Fix: Use fastboot flash recovery twrp.img followed immediately by fastboot reboot recovery instead.

Issue 3: TWRP Cannot Read Internal Storage / Asks for Password

• Cause: Your data partition is encrypted.
• Fix: In TWRP, go to Wipe → Format Data, type "yes", and confirm. Then reboot back to TWRP. Note: This erases all data on internal storage.

Issue 4: Stuck in Bootloop After TWRP Installation

• Causes: Incompatible TWRP version, skipped formatting data, or incorrect flashing procedure.
• Fixes:
  • Reboot to TWRP and wipe cache + dalvik/art cache
  • If that doesn't work, format data in TWRP
  • If all else fails, you may need to flash the stock firmware using Realme Flash Tool or SPD Flash Tool to restore your device, then try again with a different TWRP version

Issue 5: Fastboot Doesn't Detect Device

• Solutions:
  • Install or reinstall Realme USB drivers
  • Use a rear USB 2.0 port directly on the motherboard
  • Try a different high-quality USB data cable
  • On Windows 10/11, you may need to disable driver signature enforcement temporarily

Important Tips for Success

1. Always use the correct TWRP build specifically made for Realme C21Y (RMX3261/RMX3263). Using a TWRP built for another device, even a similar Realme model, will cause issues.
2. The "boot directly to TWRP" step is non-negotiable. This is the #1 mistake that causes TWRP to be overwritten.
3. Make TWRP permanent from within TWRP. Either use the "Flash Current TWRP" option or flash a multi-disable zip;   don't skip this protection step.
4. USB 2.0 ports are more reliable for flashing operations than USB 3.0/3.1 ports, which can sometimes cause detection issues.
5. Original cables are best. Cheap or charge-only cables are the #1 cause of "device not detected" errors.

Conclusion

Installing TWRP recovery on your Realme C21Y is a straightforward process when you follow the correct procedure and understand the critical "anti-gagal" steps. The entire process boils down to: unlock the bootloader → flash TWRP via fastboot → boot DIRECTLY to TWRP without letting the system boot first → make TWRP permanent from within TWRP.

By following this fail-proof guide carefully, you've successfully avoided the most common pitfall:   the stock recovery automatically overwriting TWRP on first boot. You now have a powerful custom recovery installed permanently, ready to help you explore the full potential of your Realme C21Y through backups, custom ROMs, rooting, and system modifications.

Remember to always make a full NANDroid backup before making any major changes to your system. With TWRP by your side, you can experiment freely, knowing you always have a way back to a working state. Enjoy your newly liberated Realme C21Y!