How to Flash Android Firmware Using Fastboot and ADB
Fastboot and ADB are the universal tools for Android firmware flashing, bootloader unlocking, and partition management — built directly into Android Platform Tools by Google. This guide covers setup, device connection, bootloader unlock, and flashing firmware on any Android device.
Pre-Flight Checklist
Complete ALL items before proceeding. Skipping any step increases the risk of bricking your device.
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Backup all data to Google Drive, PC, or external storageFastboot flashing typically wipes data. Use Google Backup and a file manager backup.
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Battery charged above 50%Fastboot operations can take time. Ensure your device has adequate charge.
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Bootloader is UNLOCKED on your deviceUnlike SP Flash Tool or Odin, Fastboot requires an unlocked bootloader for most flashing operations. Check Settings → Developer Options → OEM Unlock.
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Android Platform Tools (ADB & Fastboot) installed on PCDownload from Google's official Android developer site. Add to your system PATH for easy access.
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USB Debugging enabled in Developer OptionsSettings → About Phone → tap Build Number 7 times → Developer Options → USB Debugging.
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Correct firmware or image file downloadedEnsure you have the correct .img file(s) or factory image ZIP for your exact device model.
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Vendor USB drivers installed (Google, Qualcomm, etc.)For Pixels: install Google USB Driver. For other brands: install their specific ADB driver.
Guide Steps
Download Android Platform Tools from Google and extract to a folder. Open a Command Prompt (Windows) or Terminal (Mac/Linux) in that folder and test:
Both commands should return a version number. If you get "command not found", add the Platform Tools folder to your system PATH environment variable.
If your bootloader is not already unlocked:
- Enable Developer Options: Settings → About Phone → tap Build Number 7 times
- Go to Settings → Developer Options → enable OEM Unlocking
- Connect device to PC, open terminal:
Once in bootloader/fastboot mode:
Confirm the unlock on your device screen using the volume keys and power button. This will factory reset your device.
Method 1 — via ADB (recommended, device must be on):
Method 2 — via hardware buttons (device must be OFF):
- Google Pixel: Power + Volume Down
- OnePlus: Power + Volume Up
- Xiaomi/Redmi: Power + Volume Down
- Motorola: Power + Volume Down
Verify your PC recognizes the device in fastboot mode:
You should see your device serial number. If nothing shows, reinstall drivers.
Option A: Flash a single .img file
Option B: Flash Google Pixel factory image (full wipe)
Extract the factory image ZIP. Inside you'll find a flash-all.sh (Mac/Linux) or flash-all.bat (Windows). Run it:
Option C: Wipe data partition manually
After flashing, reboot:
Or to reboot into recovery:
The first boot will take several minutes. Do not panic if it takes up to 10 minutes — Android is optimizing apps.
Congratulations! Flash Successful!
You've successfully completed all steps. Your device should now be running the new firmware. If it's booting normally — you're done! Check the troubleshooting section below if you encounter any issues.
Troubleshooting & FAQ
Common errors and their solutions. Read this before asking for help.
Most common causes:
- Wrong driver — install Google USB Driver or your device's specific ADB driver
- Device isn't actually in fastboot mode — verify screen shows "Fastboot Mode" or "Bootloader"
- Bad USB cable — try the original cable
- On Windows: run Command Prompt as Administrator
This means fastboot is connected but doesn't recognize the command. Possible causes:
- You're not actually in fastboot mode (you might be in recovery or ADB mode instead)
- Using an older fastboot version — update Android Platform Tools
- The partition name is wrong for your device (e.g., some use "boot_a" and "boot_b" for A/B partition schemes)
Modern devices (Pixel 2+, most flagships 2019+) use A/B partition scheme. To flash both slots:
Or use:
The factory image flash-all script handles this automatically.
Yes, on most devices:
However, you must flash official stock firmware before re-locking. Re-locking with custom software will hard brick your device. The device will factory reset again on lock.
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