To follow the instructions in this guide, you will need adb and fastboot.
These tools are provided as part of the Android SDK:
https://developer.android.com/studio
Before flashing this recovery image to your SHIELD, connect your SHIELD
via USB to the PC where you downloaded this recovery image.
Next, put your SHIELD into fastboot mode using one of the following methods:
SW method:
– Boot to android home screen
– Connect the device to linux/windows system
– Open terminal (on linux); command prompt (on windows).
– Type “adb reboot bootloader” in terminal/command prompt
HW method:
– Turn off the device
– Press and hold “Back”+”Home”+”SHIELD” buttons till device boots
To flash this recovery image to your SHIELD, run the following commands from
the directory where you extracted the recovery image package. If this is the
first time you have done this procedure, you must unlock the bootloader (see
below):
fastboot flash recovery recovery.img
fastboot flash boot boot.img
fastboot flash system system.img
fastboot flash userdata userdata.img
fastboot flash staging blob
fastboot flash dtb tegra114-roth.dtb
Unlocking the Bootloader
Your SHIELD may have shipped with a locked bootloader. To update the device,
you must unlock the bootloader using the following:
– fastboot oem unlock
– Press the Home button on the device to highlight “Unlock”.
– Press the Shield button to confirm the unlock. Your device’s bootloader is now unlocked.