Guide to US LTE Bands on the Xiaomi Qin F21 Pro (Excerpt from XDA Forums)

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Based on the method by XDA Forums user CatStoleTheCrown
Unlock LTE Bands 2, 4, 12, 13, 17, 66, 71 (from the US Qin F30 Kosher)

I broke each step up to make it more clear.

:police_car_light: Disclaimer

Proceed at your own risk. Flashing or modifying your device could result in a non-working (bricked) phone if done incorrectly. Backup everything and be cautious.

:white_check_mark: Requirements

You only need to follow the above-linked custom firmware guide up to the point of flashing boot_2.img in TWRP – rooting is optional.

:hammer_and_wrench: Step-by-Step Guide

Step 1: Backup Identifiers

Go to Settings > About Phone, and write down:

  • IMEI
  • WiFi MAC Address
  • Bluetooth Address

Use the included .txt file to record them.

Step 2: Boot into TWRP

Power off the phone. Then hold:

  • Heart/Owl button (top left)
  • Star button (bottom left)
    Keep holding until you see the Douqin logo and enter TWRP.

Step 3: Backup Original NV Partitions via ADB

Connect phone via USB (TWRP allows ADB access). Run:

adb pull /dev/block/by-name/nvdata
adb pull /dev/block/by-name/nvram
adb pull /dev/block/by-name/nvcfg

Save these files somewhere safe – they contain your unique hardware identifiers!

Step 4: Power Off the Device

In TWRP, tap Reboot > Power Off.

Step 5: Flash LTE Band Partitions via SP Flash Tool

  1. Launch SP Flash Tool
  2. Load the scatter file:
    MT6761_Android_scatter - edited.txt
  3. Uncheck everything except:
    • nvcfg
    • nvdata
    • nvram
    • md1img_a

    :warning: Uncheck preloader! It must be present for flashing, but should NOT be flashed.

  4. Ensure the file paths for each are set correctly.
  5. Click Download (green arrow).
  6. With phone powered off, hold Back button (top right) and plug in the USB.
  7. Flashing should begin. Wait for success confirmation.

Step 6: Restore Identifiers via SN Write Tool

  1. Open SN Write Tool
  2. Set:
    • ComPort: USBVCOM
    • Target Type: Smart Phone
  3. Click System Config
    • Under Write Option, check:
      • IMEI
      • BT Address
      • WiFi Address
    • Under Database File:
      • Check both “Load AP DB from DUT” and “Load Modem DB from DUT”
    • Click MD1_DB and choose:
      MDDB_InfoCustomAppSrcP_MT6761_S00_...EDB
    • Click AP_DB and choose:
      APDB_MT6761_S01__W1947...
  4. Click Save and return to main window
  5. Click Start. Enter:
    • IMEI (without spaces)
    • BT Address (without colons)
    • WiFi Address (without colons)
  6. Hold Back button, plug in phone, and click OK
  7. Wait for Green PASS confirmation

    If a second window pops up, just close it if you already saw PASS.

Step 7: Boot Up & Verify

Turn on your phone and go to Settings > About Phone. Ensure:

  • IMEI is correct
  • WiFi MAC is correct
  • Bluetooth MAC is correct

To check active bands:

  1. Dial: *#*#3646633#*#*
  2. Navigate to Band Mode
  3. Scroll to confirm bands 2, 4, 12, 13, 17, 66, 71 are active.

:pushpin: Notes

  • BACKUP your partitions and identifiers before doing anything.
  • If you skip SN Write Tool, you’ll get dummy identifiers that may conflict with other devices.
  • This method does not unlock your bootloader — you must already have it unlocked.
  • Band coverage includes:
    • T-Mobile
    • Verizon
    • Some AT&T support, depending on region.

Huge credit to CatStoleTheCrown on XDA Forums for this amazing work in enabling US LTE compatibility on the Qin F21 Pro.

2 Likes
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Ask/Discuss here: Qin F21 Pro Topic

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Let me just add my 2 cents:

  • Bootloader unlocked: OK
  • TWRP: Nah. Why? Skip it.
  • SP Flash Tool: Nah, use fastboot.
  • Preloader: Just delete it from the folder, so you don’t have to uncheck it.
  • BT & WiFi: Unnecessary. Only IMEI.
  • Catstolethecrown: Like, it’s so obvious… get an F30 and pull for F21. But yeah, give credit.