h1. Nexus S (I902x) Installation *Warning: installing an operating system, such as Replicant, may void your device's warranty and will erase the data stored on the device.* h2. Prerequisites In order to install Replicant on your device, it is assumed that you have a computer running a GNU/Linux operating system and everything necessary to connect your device to the computer through USB available. Moreover, it is assumed that anyone performing the installation knows how to use command lines in a terminal and has basic knowledge about it. h2. Downloading the files The first step in the installation process is to download and set up the files that will be used to install Replicant to the device. The files must be downloaded on your computer first. 1. Find out what the latest image is: check out the @Last image@ part of the general table on [[NexusSI902x]] 2. Download *all* the files listed for the device (including the checksum and the signatures) on [[ReplicantImages]] for the latest image 2. Make sure you have added the [[ReplicantReleaseKey|Replicant release key]] to your GPG keyring 3. Check the signature of the files: 
gpg --armor --verify path/to/replicant-4.2-crespo.zip.asc path/to/replicant-4.2-crespo.zip
gpg --armor --verify path/to/recovery.img.asc path/to/recovery.img
4. Make sure the check succeeds, *do not install anything if it doesn't*! 5. Check the checksum of the files: 
md5sum -c crespo.md5
6. Make sure the check succeeds, *do not install anything if it doesn't*! h2. Installing fastboot The fastboot tool is required to flash the recovery image to the device. Instructions to install fastboot: [[ToolsInstallation#Fastboot|ToolsInstallation]] h2. Copying the files to the device There are two means of pushing the system zip to the device: * Using the storage of the device * Using the ADB tool to perform sideload h3. Using the storage of the device 1. Make sure the device is started up and has an Android system running 2. Connect the USB cable to both the computer and the device 3. Enable USB mass storage on the device 4. Mount the mass storage on the computer 5. Copy the @replicant-4.2-crespo.zip@ file at the origin of the mass storage 6. Safely unmount the mass storage on the computer 7. Disable USB mass storage on the device h3. Installing ADB Instructions to install ADB: [[ToolsInstallation#ADB|ToolsInstallation]] h2. Preparing the device The next step in the installation process is to prepare the device for fastboot mode. 1. Make sure the device is completely turned off and the USB cable is disconnected from the device 2. Start the device by holding the following key combination: *Volume up, Power* 3. Hold the key combination until the device shows *Fastboot mode* 4. Connect the USB cable to both the computer and the device h3. Unlocking the bootloader If this is the first time you are flashing an operating system to your device, you'll have to unlock it first. If this is not the case, you can skip that part. *Beware: all data stored on the internal storage will be lost during that operation.* 1. Unlock the bootloader: 
fastboot oem unlock
2. Confirm that you want to unlock the device (using the volume keys to navigate and the power key to select) h2. Installing the images Now that both the computer and the device are set up, it is time to actually install the images to the device. 1. Install the recovery image to the device: 
fastboot flash recovery path/to/recovery.img
2. Select recovery mode (using the volume keys to navigate and the power key to select) 3. Make sure the device reboots to recovery 4. Select *install zip* (using the volume keys to navigate and the power key to select) h3. Using the storage of the device 5. Select *install zip from sdcard* 6. Select the system zip: *replicant-4.2-crespo.zip* Note: if your device was running Android 4.2 and later, it may be located in the *0* directory 7. Confirm the installation h3. Using ADB sideload 5. Select *install zip from sideload* 6. Back to the host computer, load the system zip with sideload: 
adb sideload path/to/replicant-4.2-crespo.zip
7. Make sure the file is being transfered h3. Completing the installation 8. Select *Go Back* (if necessary) to get back to the general menu 8. Select *wipe data/factory reset* 9. Confirm the data wipe by selecting *Yes -- delete all user data* 10. Select *Reboot system now* to reboot the device *Your device should now be running Replicant!*