How to Flash Stock Firmware Using Fastboot Scripts (flash-all.bat / flash-all.sh)

Many Android manufacturers distribute official factory firmware packages that include an automated Fastboot flashing script, usually named flash-all.bat (Windows) or flash-all.sh (macOS/Linux).

This method is commonly used by:

  • Google (Pixel and legacy Nexus factory images)
  • Motorola and some other OEMs
  • Smaller OEMs that publish Fastboot-based factory packages

It is one of the most reliable and transparent ways to restore a device to factory software, fix bootloops, or return from a custom ROM — when the bootloader can be unlocked and the OEM allows it.

This guide explains when Fastboot scripts are appropriate, their limitations, and a safe, end-to-end workflow for flashing stock firmware using official scripts.

What a Fastboot Flash Script Does

A Fastboot flash script is simply a file that automates a sequence of commands such as:

fastboot flash boot boot.img
fastboot flash system system.img
fastboot flash vendor vendor.img
fastboot erase userdata
fastboot reboot

Instead of flashing partitions manually, the script:

  • Executes the correct partition order and options defined by the OEM
  • Reduces human error compared to manual command entry
  • Ensures a complete factory restore when used with the correct firmware

The script does not bypass security — it still requires an unlocked bootloader and compliance with the OEM’s bootloader policy.

Who This Method Is For

Use this method only if all of the following apply:

  • ✔ Your device supports Fastboot / Bootloader mode
  • ✔ The firmware package is an official factory image that includes flash-all.bat or flash-all.sh
  • ✔ Bootloader unlocking is allowed by your OEM/carrier for your model
  • ✔ You are flashing official stock firmware for your exact device, region, and carrier

This method is NOT for:

  • ❌ Devices whose bootloader cannot be unlocked (OEM- or carrier-restricted)
  • ❌ Firmware packaged for QFIL, SP Flash Tool, Odin, OST, Mi Flash, or other OEM/service tools
  • ❌ FRP/account removal, security bypass, or cross-model/cross-region “experiments”
  • ❌ Incremental OTA packages that are not designed as full Fastboot factory images
  • ❌ Devices where the firmware package does not include an official Fastboot script

Flashing Disclaimer

Flashing firmware using Fastboot scripts:

  • Erases all user data as part of the process in most official scripts
  • Requires bootloader unlocking where the OEM permits it
  • Can permanently brick a device if the wrong firmware is used or power/USB is interrupted

FlashGuideHub is not responsible for data loss, warranty impact, or hardware damage caused by incompatible firmware or improper flashing.

Always verify:

  • Exact device model and variant (including carrier and hardware revision)
  • Matching firmware region, carrier, and Android version
  • Bootloader unlock policy for your OEM and carrier (some devices are permanently locked)

What You Need

  • A Windows, macOS, or Linux PC
  • A compatible Android device with Fastboot support
  • A reliable, data-capable USB cable
  • Android SDK Platform-Tools (ADB & Fastboot)
  • Correct USB drivers for your device (Windows)
  • Official factory firmware from the OEM that contains a Fastboot script

Preparing Your Computer

1. Install Android Platform-Tools

Download the latest Android SDK Platform-Tools from Google and extract them to a simple folder such as:

C:\platform-tools

You may optionally add this folder to your system PATH so that fastboot is available from any terminal.

2. Install USB Drivers (Windows Only)

macOS and Linux typically do not require additional USB drivers for Fastboot.

Preparing Your Phone

Enable Developer Options

  1. Go to Settings → About phone.
  2. Tap Build number 7 times to enable Developer options.
  3. Return to Settings → Developer options.
  4. Enable:
    • OEM unlocking (if present and supported by your OEM)
    • USB debugging

If OEM unlocking is missing or greyed out, your device may not support bootloader unlocking for flashing.

Unlocking the Bootloader (Required for Most Devices)

⚠️ This step wipes all data, may affect warranty, and cannot be skipped on locked devices.

  1. Power off the device completely.
  2. Boot into Fastboot / Bootloader mode:
    • Usually by holding Volume Down + Power (varies by OEM).
  3. Connect the device to your PC using a reliable USB cable.
  4. Open a terminal/command prompt in the Platform-Tools folder and verify the connection:
fastboot devices
  1. Check your OEM’s unlock documentation, then unlock the bootloader if allowed:
    • Modern devices (A/B slots, Pixels, many recent phones):
fastboot flashing unlock
  1. Some older or OEM-specific devices may use:
fastboot oem unlock
  1. Confirm the unlock on the device screen when prompted.
  2. Allow the phone to factory reset and reboot once unlocking is complete.

If your OEM/carrier does not permit bootloader unlocking, this Fastboot script method is not applicable.

Flashing Firmware Using the Script

  1. After the unlock/reset, power off the device again.
  2. Boot back into Fastboot / Bootloader mode.
  3. Extract the official factory firmware package to a simple folder (avoid spaces and special characters in the path).
  4. Open the extracted folder containing flash-all.bat / flash-all.sh.

Run the Script

  • Windows: Double-click flash-all.bat, or run it from a Command Prompt opened in that folder.
  • macOS / Linux: Open a terminal in the folder and run:
./flash-all.sh
  1. The script will automatically flash the partitions defined by the OEM.
  2. Do not disconnect the device or close the terminal while flashing.
  3. Wait for the script to complete and the device to reboot automatically.

First boot after a full factory flash can take several minutes. Do not interrupt the process unless the script clearly reports a failure.

Common Problems & Fixes

“fastboot is not recognized”

  • Open the command prompt or terminal inside the Platform-Tools folder.
  • Or add the Platform-Tools folder to your system PATH.

“Waiting for device”

  • Often a USB driver issue (Windows) or cable/port problem.
  • Try another USB cable or port.
  • Reinstall or update drivers.
  • On Windows, check Device Manager for driver status.

“Partition is locked” or write errors

  • The bootloader is not fully unlocked, or OEM restrictions still apply.
  • Verify unlock status in the bootloader screen and review your OEM’s unlock steps.

Script fails on a specific partition

  • Check that the firmware matches your exact device variant and region.
  • Re-download the factory image in case of a corrupted archive.

Final Notes

Fastboot flashing scripts are one of the cleanest and safest official flashing methods when supported by the manufacturer and used with the correct factory image.

They:

  • Do not bypass OEM security or unlock policies
  • Do not rely on third-party flashing tools
  • Follow OEM-defined partition layout and flashing logic

If your firmware does not include a Fastboot script, or if your bootloader cannot be unlocked according to OEM policy, this method is not applicable. In those cases, use the method specified by the firmware provider (e.g. OTA, recovery sideload, OEM service tools).

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