Facing issues like bootloop, system crash, or a missing IMEI on your Xiaomi 15 Ultra? You’re not alone. Problems can occur after a failed update, corrupted firmware, or third-party modifications. The good news? You can fix these problems yourself by flashing the right stock firmware and using the correct tools.
In this article, you’ll learn how to flash the Xiaomi 15 Ultra, repair its IMEI, and restore full functionality—just like it came out of the box.
What is Stock Firmware and Why It Matters
Stock firmware (also known as the ROM or flash file) is the official operating system installed by Xiaomi. It ensures your device works correctly, including hardware communication, security patches, and UI.
When your Xiaomi 15 Ultra becomes unstable, stuck on the logo, or bricked, flashing stock firmware can bring it back to life.
When Should You Flash Xiaomi 15 Ultra Firmware?
Use stock firmware flashing when:
- Your Xiaomi 15 Ultra is stuck in a bootloop or logo screen
- The phone is soft-bricked or not booting
- Apps are crashing or performance is poor
- You want to unroot and go back to stock MIUI
- You want to downgrade/upgrade Android safely
- You need to restore a lost or corrupted IMEI
What You Need Before Flashing
Prepare these tools and files before you start:
✅ Correct firmware for Xiaomi 15 Ultra (Global, China, or EU version)
✅ Xiaomi USB Drivers
✅ Mi Flash Tool (Fastboot version)
✅ Unlocked bootloader (required for flashing)
✅ Working Windows PC and USB cable
✅ Backup of all important data
⚠️ Note: Bootloader unlock is mandatory on newer Xiaomi flagships like the 15 Ultra. You’ll need to apply for unlock via Xiaomi’s official unlock tool.
How to Flash Xiaomi 15 Ultra Firmware – Step-by-Step
Let’s walk through the full process to flash your Xiaomi 15 Ultra using Fastboot ROM.
Step 1: Download the Right Firmware
- Visit https://mirom.com or the official Mi Flash ROM page.
- Search for Xiaomi 15 Ultra and choose the firmware that matches your region.
- Download the Fastboot version (not the Recovery version). It ends with
.tgz.
Step 2: Unlock the Bootloader (If Not Done)
- Download the Mi Unlock Tool.
- Enable Developer Options > OEM Unlocking & USB Debugging.
- Link your Mi Account and unlock the bootloader (takes up to 7 days wait for approval).
Step 3: Install Xiaomi USB Drivers and Mi Flash Tool
- Install Mi USB Drivers on your PC.
- Install Mi Flash Tool, extract it, and run as Administrator.
Step 4: Boot into Fastboot Mode
- Power off the phone.
- Hold Volume Down + Power to enter Fastboot Mode.
- Connect to PC using a USB cable.
Step 5: Load Firmware into Mi Flash Tool
- Extract the downloaded
.tgzfirmware file. - In Mi Flash Tool, click “Select” and browse to the firmware folder.
- At the bottom, choose “clean all” (recommended for fresh installs).
Step 6: Start Flashing
- Click “Flash” and wait for 5–10 minutes.
- Once completed, you’ll see “Success” in green.
- Your Xiaomi 15 Ultra will reboot automatically.
✅ Congratulations! Your phone is now running official stock firmware again.
How to Repair IMEI on Xiaomi 15 Ultra
If you see “Invalid IMEI”, “No service”, or your SIM isn’t detected after flashing, your phone’s IMEI may be corrupted.
⚠️ Legal Warning: IMEI repair is only allowed on your original device and must match the official IMEI printed on the box.
Method 1: Using QCN Backup/Restore (Qualcomm Method)
Since the Xiaomi 15 Ultra uses a Qualcomm Snapdragon processor, use this method:
- Download QPST Tool or QFIL Tool.
- Get the QCN backup file for Xiaomi 15 Ultra or create a backup beforehand.
- Enable DIAG mode (via ADB or engineering app).
- Use QPST/QCN Restore to rewrite the original IMEI.
Method 2: Using Professional Tools (Advanced Users)
Some advanced methods involve using:
- MRT Tool
- Hydra Tool
- UMT QcFire
These tools require a license/dongle and are used by professional repair technicians. They can safely rewrite IMEI using EDL mode (Emergency Download Mode).
Why Flashing the Correct Firmware Matters
- ✅ Keeps your device secure and fast
- ✅ Restores original MIUI functionality
- ✅ Fixes IMEI/network/bootloop issues
- ✅ Ensures OTA updates continue to work
- ✅ Removes bugs and crashes from custom ROMs
Using the wrong firmware may brick your device or permanently disable features like the camera, 5G, or fingerprint sensor.
Common Flashing Issues and Solutions
| Problem | Solution |
|---|---|
| Phone not detected by PC | Reinstall USB drivers or try a new cable |
| Mi Flash error or stuck | Use another firmware version |
| Bootloop after flashing | Wipe data from stock recovery |
| Invalid IMEI after flashing | Use QCN or DIAG tools to restore IMEI |
| Fastboot fails or error | Unlock bootloader again or reinstall Mi Tool |
Final Thoughts
Flashing firmware on the Xiaomi 15 Ultra is a powerful way to fix serious software problems and restore your phone to factory condition. Whether you’re unbricking your device, removing a bootloop, or repairing IMEI, this guide has you covered.
Just remember:
- Always use official firmware
- Unlock the bootloader safely
- Backup your data
- Be cautious with IMEI tools—only repair your own device
With care and the right tools, your Xiaomi 15 Ultra can be as smooth and powerful as it was on day one.
