The Xiaomi Redmi S2, known as the Redmi Y2 in India (codename ysl), was a standout budget phone in 2018, specifically designed for selfie lovers. With its 16MP front-facing camera and dedicated LED flash, paired with the legendary and reliable Snapdragon 625 chipset, it offered incredible value.
Impressively, Xiaomi supported the device all the way up to the MIUI 12 update. However, this final major release proved to be very demanding for the phone's hardware. Many users reported significant lag, poor battery life, and general instability after updating, making the device frustrating to use. If your Redmi S2/Y2 is struggling to keep up, a clean firmware flash is the most effective solution to restore its performance, fix persistent bugs, or unbrick it from a failed update.
This guide provides everything you need to refresh your ysl:
Why You Might Need to Flash Your Redmi S2 / Y2
For an older device like this, flashing the final firmware is a powerful troubleshooting step.
Quick Device Overview (Codename: ysl)
Required Tools & Downloads
Before you start, download the firmware for your desired region and all the essential tools.
Flashing Methods
Method 1: Flashing Official Stock ROM (Fastboot Mode)
This is the best method to fix lag, unbrick your phone, or return to a completely stock state.
➡ The device will reboot automatically. This first boot can take 10-15 minutes.
Method 2: Installing Xiaomi.eu ROM (For Better Performance)
If stock MIUI 12 is still too slow, the lighter Xiaomi.eu ROM is an excellent alternative.
➡ Your phone will now boot into a faster, cleaner version of MIUI 12.
FAQs
Q1: Will this update my phone to Android 10?
No. The Redmi S2/Y2 has reached its official End of Life (EOL) for software support. The final Android version is Android 9 Pie, which is what these MIUI 12 builds are based on.
Q2: Why is my phone so slow after the official MIUI 12 update?
MIUI 12 is a visually rich and heavy OS. The Snapdragon 625, while reliable, struggles to run it smoothly. A clean flash (as described in Method 1) helps significantly, but for the best possible speed, the debloated Xiaomi.eu ROM is recommended.
Q3: Is the Redmi Y2 the same as the Redmi S2?
Yes, they are identical phones (codename ysl). The only difference was the name used for marketing in India versus the global market. All firmware is cross-compatible.
Q4: My camera app is lagging and crashing. Will this fix it?
Yes. If the camera issues are caused by a software bug, a full clean flash of the official firmware will reinstall all the necessary camera libraries and drivers, which almost always resolves these problems.
Troubleshooting & Common Errors
Impressively, Xiaomi supported the device all the way up to the MIUI 12 update. However, this final major release proved to be very demanding for the phone's hardware. Many users reported significant lag, poor battery life, and general instability after updating, making the device frustrating to use. If your Redmi S2/Y2 is struggling to keep up, a clean firmware flash is the most effective solution to restore its performance, fix persistent bugs, or unbrick it from a failed update.
This guide provides everything you need to refresh your ysl:
- ✔ Download links for the final official MIUI 12 Fastboot ROMs (Global, China, Russia)
- ✔ The lighter, performance-oriented Xiaomi.eu custom ROM
- ✔ All the necessary drivers and flashing tools for a smooth process
- ✔ Step-by-step instructions for both Mi Flash Tool and custom recovery methods
- ✔ Answers to common questions about performance issues on MIUI 12
Why You Might Need to Flash Your Redmi S2 / Y2
For an older device like this, flashing the final firmware is a powerful troubleshooting step.
- Fix Severe Lag & Stutter on MIUI 12 → This is the primary reason for most users. A clean installation removes leftover files from previous updates, significantly improving the phone's responsiveness.
- Improve Poor Battery Life → If your battery drains quickly after the MIUI 12 update, a full flash can resolve underlying software conflicts and rogue processes.
- Resolve Camera App Bugs → Fix issues where the camera app, the phone's main feature, freezes, crashes, or fails to process images correctly.
- Unbrick from a Failed Update → If your phone is stuck in a bootloop (on the Mi logo) after a failed OTA update, a Fastboot flash is the definitive way to recover it.
- Switch Regions → Easily convert an Indian Redmi Y2 to the Global Redmi S2 version, or flash a Chinese unit with a Global ROM to get Google services.
Quick Device Overview (Codename: ysl)
- Model: Xiaomi Redmi S2 (Global) / Redmi Y2 (India)
- Release Year: 2018
- Chipset: Qualcomm Snapdragon 625
- Display: 5.99” HD+ IPS (720×1440)
- Battery: 3080 mAh
- OS at Launch: MIUI 9 on Android 8.1 Oreo
- Final Official OS: MIUI 12 on Android 9 Pie (End of Life)
- Codename: ysl
The Redmi S2 and Redmi Y2 are the exact same phone with the codename ysl. The firmware provided here is compatible with both models, allowing for cross-regional flashing (e.g., Global ROM on an Indian unit).
Required Tools & Downloads
Before you start, download the firmware for your desired region and all the essential tools.
| Tool / File | Purpose | Download Link |
|---|---|---|
| Mi Flash Tool | For flashing official Fastboot ROMs (.tgz) | Download Latest Version |
| Xiaomi USB Drivers | Ensures your PC properly detects the device | Driver Pack |
| Mi Unlock Tool | To unlock the device's bootloader (required) | Official Unlock Page |
| Custom Recovery (TWRP) | For flashing .zip ROMs like Xiaomi.eu | Official TWRP for YSL |
| Fastboot ROM (China) | China Stable MIUI 12 | V12.0.4.0.PEFCNXM |
| Fastboot ROM (Global) | Global Stable MIUI 12 | V12.0.2.0.PEFMIXM |
| Fastboot ROM (Russia) | Russia Stable MIUI 12 | V12.0.1.0.PEFRUXM |
| Xiaomi.eu ROM (Custom) | Lighter, debloated custom ROM for better performance | V12.0.4.0.PEFCNXM |
Flashing Methods
Method 1: Flashing Official Stock ROM (Fastboot Mode)
This is the best method to fix lag, unbrick your phone, or return to a completely stock state.
- Unlock Bootloader: You must unlock the bootloader via the Mi Unlock Tool. This is a one-time process and will erase all your data.
- Boot into Fastboot Mode: Power off your Redmi S2/Y2. Then, press and hold the Power + Volume Down buttons together until the Fastboot logo appears.
- Extract Firmware: On your PC, use 7-Zip or WinRAR to extract the downloaded .tgz firmware file twice, until you have a folder with an images directory and flashing scripts.
- Open Mi Flash Tool: Launch the application. Click "select" and choose the firmware folder you just extracted.
- Connect Your Phone: Connect your device to the PC. Click "refresh" in Mi Flash Tool, and your phone's ID should appear in the list.
- Select "clean all": At the bottom of the tool, it is essential to select the "clean all" option to ensure a clean install and fix performance issues.
- Click "Flash": The flashing process will begin. Wait until the progress bar turns green and shows a "success" message.
➡ The device will reboot automatically. This first boot can take 10-15 minutes.
Method 2: Installing Xiaomi.eu ROM (For Better Performance)
If stock MIUI 12 is still too slow, the lighter Xiaomi.eu ROM is an excellent alternative.
- Unlock Bootloader & Install TWRP: Ensure your bootloader is unlocked and you have installed a compatible TWRP custom recovery.
- Boot into TWRP: Power off the phone. Press and hold Power + Volume Up to boot into the TWRP recovery menu.
- Wipe Data: Perform a factory reset by going to Wipe → Format Data and typing "yes" to confirm. This is required.
- Transfer ROM File: Connect the phone to your PC and copy the downloaded Xiaomi.eu .zip ROM to the internal storage.
- Install the ROM: In TWRP, tap Install, find the ROM .zip file, and swipe the slider to start the installation.
- Reboot System: After the installation is complete, tap "Reboot System."
➡ Your phone will now boot into a faster, cleaner version of MIUI 12.
FAQs
Q1: Will this update my phone to Android 10?
No. The Redmi S2/Y2 has reached its official End of Life (EOL) for software support. The final Android version is Android 9 Pie, which is what these MIUI 12 builds are based on.
Q2: Why is my phone so slow after the official MIUI 12 update?
MIUI 12 is a visually rich and heavy OS. The Snapdragon 625, while reliable, struggles to run it smoothly. A clean flash (as described in Method 1) helps significantly, but for the best possible speed, the debloated Xiaomi.eu ROM is recommended.
Q3: Is the Redmi Y2 the same as the Redmi S2?
Yes, they are identical phones (codename ysl). The only difference was the name used for marketing in India versus the global market. All firmware is cross-compatible.
Q4: My camera app is lagging and crashing. Will this fix it?
Yes. If the camera issues are caused by a software bug, a full clean flash of the official firmware will reinstall all the necessary camera libraries and drivers, which almost always resolves these problems.
Troubleshooting & Common Errors
- Bootloop after flashing: If the phone is stuck on the Mi logo after rebooting, you likely did not perform a clean flash. Force the phone back into Fastboot mode (hold Power + Vol Down) and flash again using the "clean all" option.
- Mi Flash Tool "could not find file" error: This means you did not extract the .tgz file correctly. Make sure you extract it twice until you have a folder with the images directory, not just a single .tar file.
_ - "This device is locked": This is a Mi Account lock, not a SIM lock. It means the phone is linked to a previous owner's account. A standard flash will not remove this server-side lock.
- Performance is still poor after flashing stock ROM: While a clean flash helps, the hardware has its limits. Try disabling system animations in Developer Options and using "Lite" versions of apps like Facebook and Messenger to further improve speed.