rebootbootloader

Rebooting into the bootloader, often written or spoken as reboot-bootloader, is a device management action used on many Android devices to enter bootloader or fastboot mode. The bootloader is a small program that runs before the operating system and provides low-level access for flashing software, unlocking the bootloader, and performing maintenance tasks. Rebooting into this mode is a common step when developers or advanced users need to flash factory images, custom recoveries, or other system partitions.

The reboot can be initiated in several ways. From a device with USB debugging enabled, the command adb reboot-bootloader reboots the device into bootloader mode. From a PC with Android platform-tools installed, the commands fastboot devices confirm connection, followed by fastboot flashing unlock (or fastboot oem unlock on older devices) to unlock the bootloader. Once in bootloader/fastboot mode, additional commands such as fastboot flash to write images, fastboot reboot to leave bootloader, or device-specific flashing commands can be used. Some devices also support entering bootloader mode directly through hardware key combinations, typically by holding power and a volume key during boot.

Limitations and cautions apply. Not all devices support fastboot, and modifying boot or system partitions can brick the device if done improperly. Unlocking the bootloader may erase user data and can void warranties. Users should follow device-specific instructions and ensure they have verified official images and tools before flashing.

See also: bootloader, fastboot, adb.