Fastboot mode: tutorial of use and list of commands for Android

The Fastboot, same as him ADB is a tool that allows us to communicate with an Android device directly from the PC. It consists of a series of commands with which we can send orders to the phone or tablet, and they can serve us both to root a terminal and to flash a new firmware or try to repair it from a brick.

Unlike ADB, which we can use without having access to the recovery or the operating system, in the case of fastboot, we can make use of it directly from the bootloader mode or when ADB commands don't even work. A true lifesaver and a supreme tool, folks!

First of all, make sure you have installed the device drivers on your PC

If we want to operate using fastboot, it is important that we install all the Android terminal drivers on the PC, as well as the corresponding fastboot package. You can get more information about it in this other post.

List of commands and structure for fastboot

The number of fastboot commands is quite large, and although we will often only use a couple of them, it is interesting to know the ecosystem of functions that the tool offers.

How to use fastboot

The fastboot commands follow the following structure:

fastboot []

Fastboot command list

update flash device from
flashallflash boot + recovery + system
flash []write a file to a flash partition
erase delete a flash partition
format format a flash partition
getvar show a variable from the bootloader
boot []download and boot the kernel
flash: raw boot []create a boot image and flash it
deviceslist of connected devices
continuecontinue with autostart
rebootrestart the device normally
reboot-bootloaderreboot device in bootloader
helpshow help message

Options list

-wdelete user data, cache and format
if the partition type supports it.
-ordon't delete partition before formatting
-s specify device serial number
or path to device port
-lwith «devices» it shows the path of the devices.
-p specify product number
-c override kernel command line
-i specify the vendor id of a custom USB
-b specifies the base address of a custom kernel
-n specify nand page size. Default: 2048
-S [K | M | G]automatically discard files larger than
indicated size. 0 to disable.

In addition to these we also have other commands, such as:

fastboot oem unlock (to unlock the bootloader)

fastboot oem lock (to lock the bootloader)

User guide: a couple of practical examples to familiarize ourselves with fastboot

Before starting to launch commands, the first thing to do is make sure that the fastboot has detected the Android phone that we just connected to the PC. To do this, we launch the following command:

fastboot devices

If everything has gone correctly, we will see the identification number of our connected device on the screen. If it does not show anything, it means that something has not gone well (check drivers etc.).

If we are going to flash files and images, it is important that all files are located in the same path from where we execute the commands in ms-dos.

All the images and firmware files are in the "adb" folder.

From here we can do whatever we want. For example, we can install a custom recovery with the following commands:

fastboot erase recovery     – – we erase the current recovery

fastboot flash recovery recovery.img  – – where "recovery.img" corresponds to the new recovery that we want to flash

Now that we have a custom recovery, we can install a custom ROM or an official firmware. We could do it from the new recovery that we just installed (TWRP or any other) or from the same fastboot.

fastboot erase system –w   - - we delete the system partition

fastboot erase boot    - - we delete the boot

fastboot update   – – we flash the new ROM, where "" corresponds to the ROM we want to install

fastboot reboot  - - we restart the device

If instead of installing a ROM we want to do a complete erase previous (so we make sure that the terminal is clean as the whistle), we can also do it from the fastboot:

fastboot erase system

fastboot erase data

fastboot erase cache

We can also flash only some parts or images of the firmware of our Android. We can go one by one or install only the one that interests us:

fastboot flash userdata data.img

fastboot flash system system.img

fastboot flash boot boot.img

fastboot reboot

Next, I also leave you a practical example. The other day I was flashing a Yotaphone, and finally I ended up manually installing all the files that make up the firmware.

All the files were stored in the "firmware" folder inside the folder where I have all the adb drivers. The commands to execute were the following (you can mold this example to the files that make up the firmware of your Android):

fastboot flash aboot firmware / emmc_appsboot.mbn

fastboot flash boot firmware / boot.img

fastboot flash cache firmware / cache.img

fastboot flash modem firmware / radio / NON-HLOS.bin

fastboot flash sbl1 firmware / radio / sbl1.mbn

fastboot flash rpm firmware / radio / rpm.mbn

fastboot flash tz firmware / radio / tz.mbn

fastboot flash userdata firmware / userdata.img

fastboot flash -S 512M system firmware / system.img

fastboot reboot

I hope that this little tutorial has helped you to learn more about this interesting platform that is Android, and as always, you hesitate to leave your impressions and ideas in the comments area.

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