Convert your Android device into USB keyboard/mouse, control your PC from your Android device remotely, including BIOS/bootloader.

You will need Nexus 7 2012 WiFi (Grouper), with Android 4.4.2 installed.

• Plug your device into PC using USB cable.
• Power off the device.
• Hold Volume Down button and Power button for 5 seconds, to enter fastboot mode.
• Copy appropriate fastboot executable from the directory fastboot.
• Launch command fastboot oem unlock
• Confirm unlock action by pressing Power button. This will factory reset your device.
• Copy boot.img from directory nexus7-2012-wifi-grouper.
• Launch command fastboot flash boot boot.img.
• Reboot your device using Power button.
• Install and run USB Keyboard app.

You have to run all following commands on Linux. Windows is not supported.

To compile USB Keyboard app, install Android SDK and NDK from site http://developer.android.com/ , go to http://github.com/ and create an account there, and launch commands

git clone git@github.com:pelya/commandergenius.git
cd commandergenius
git submodule update --init --recursive
rm -f project/jni/application/src
ln -s hid-pc-keyboard project/jni/application/src
./changeAppSettings.sh -a
android update project -p project

Add string <uses-permission android:name="android.permission.ACCESS_SUPERUSER"/> to file project/AndroidManifest.xml, and launch ./build.sh

To compile kernel, launch commands

git clone https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6
git clone https://android.googlesource.com/kernel/tegra.git
export PATH=`pwd`/arm-eabi-4.6/bin:$PATH
export ARCH=arm
export SUBARCH=arm
export CROSS_COMPILE=arm-eabi-
cd tegra
git checkout android-tegra3-grouper-3.1-kitkat-mr1
patch -p1 < ../kernel-tegra.patch
make tegra3_android_defconfig
make -j4

To compile boot.img, launch commands

mkdir ~/bin
export PATH=~/bin:$PATH
curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
chmod a+x ~/bin/repo
mkdir aosp
cd aosp
repo init -u https://android.googlesource.com/platform/manifest -b android-4.4.2_r1
repo sync
cp -f ../tegra/arch/arm/boot/zImage device/asus/grouper/kernel
patch -p1 < ../ueventd.patch
make -j4 TARGET_PRODUCT=aosp_grouper TARGET_BUILD_VARIANT=userdebug

You then can find boot.img in directory aosp/out/target/product/grouper.

I'm planning to add remote control functionality, with live camera feed, so you can turn your Nexus 7 into an overpriced remote desktop / KVM switch solution.