How to Fix a Stuck Android Update (Bootloop) Using ADB and Fastboot

After an over‑the‑air (OTA) update, many users discover their phone stuck on the Android logo, looping endlessly. The device appears to be dead, but the hardware is fine – the system partition simply failed to boot. This tutorial shows how to break the loop using the official Android debugging tools adb and fastboot, without rooting or installing third‑party firmware.

Before you start

• Charge the phone to at least 70 %. Flashing partitions drains power quickly.
• Use a genuine USB‑C/USB‑Micro cable and a USB‑2.0 or 3.0 port on a Windows, macOS, or Linux PC.
• Install the Android Platform‑Tools (includes adb and fastboot).
• Download the official factory image for your exact device model from the manufacturer’s site (Pixel, OnePlus, Xiaomi, etc.). Do NOT use random ZIPs from forums.
• Back up any data you can still access (e.g., via adb pull /sdcard/ if the device boots into recovery).
• Read the bootloader unlock warning: unlocking will erase all user data on most devices.

Understanding why a bootloop happens

During an OTA, the update package replaces system files, updates the boot image, and may modify the radio firmware. If any step fails – due to corrupted download, insufficient storage, or a power interruption – the boot image may become mismatched with the system partition. The bootloader then cannot hand off control, resulting in a perpetual “Android is starting” loop.

Because the problem is at the partition level, normal recovery options (factory reset, cache wipe) rarely help. Re‑flashing the original system image restores the expected partition layout and resolves the loop.

Step‑by‑step rescue procedure

fastboot devices

Troubleshooting common failures

• Fastboot does not recognize the device
  • Re‑install OEM USB drivers (Windows) or add a udev rule for Android devices (SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666", GROUP="plugdev").
  • Try a different USB cable or port; some cables are charge‑only.
• “fastboot: command not found”
  • Ensure the platform-tools directory is added to your system PATH, or run the commands from inside that folder.
• Flashing fails with “FAILED (remote: ...)”
  • Most often the bootloader is still locked. Follow Step 4 to unlock, or use the fastboot flashing unlock_critical command if the OEM separates critical partitions.
  • Check that you downloaded the correct image for your exact model (including carrier variant).
• Device re‑enters bootloop after flash‑all
  • It may indicate a hardware‑level issue (e.g., failing eMMC). Try flashing only boot and system to see if the problem persists.
  • Some OEMs ship a “partial” OTA that expects a newer radio version. In that case, flash the radio.img first, then the rest.
• Phone gets stuck on fastboot screen after flashing
  • Power off the device (hold power for 10 seconds) and boot into recovery (usually Power + Volume Up). From recovery, select “Reboot system now”.

Safety notes and best practices

• Always keep a copy of the original factory image in case you need to revert.
• If your device is still under warranty, flashing a factory image typically does not void it, but unlocking the bootloader might.
• Do not interrupt the flashing process. A power loss mid‑flash can brick the device.
• When using the manual method, flash partitions in the order: bootloader → radio → boot → system → vendor → other. This mirrors the script’s order and avoids dependency issues.

When to seek professional help

If after multiple attempts the phone still refuses to boot, the problem may be deeper than a software mismatch – for example, a corrupted eMMC chip or a failed hardware component. In such cases, contact the manufacturer’s support or a certified repair shop.

By following this guide, you should be able to rescue most Android devices that have fallen into a bootloop after an OTA update, using only free, official tools and images. The same workflow applies to Pixel, OnePlus, Xiaomi, and many other fastboot‑capable phones, making it a versatile addition to any Android troubleshooting toolbox.