How to re-lock your bootloader

Here are the instructions for re-locking your bootloader, which you'll usually want to do if you need to return your phone for a warranty claim.

Note / FYI: re-locking the bootloader does NOT wipe your device (unlocking does, however).

Here's the "TL;DR" (too-long, didn't read) version for those that don't have USB connectivity issues and already know how to use fastboot:

Code:

fastboot devices         (verify fastboot connectivity)
fastboot oem lock        (re-lock the device)

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And here are the full, detailed instructions (click the "Show" button below):

A. if you already have the Android SDK installed with both the adb and fastboot utilities, go ahead and skip to step B.

If you don't have both adb and fastboot installed anywhere, it might be easiest to download and extract the sdk-tools.zip file referenced in the "Mini-SDK" section of this thread ADB Guide to a folder on your PC of your choosing (take note of this folder/directory's name).

B. turn off (power down) your device

C. connect the USB cable between the phone and your PC if you haven't already

D. on your PC, start-up a terminal session (Windows Command Prompt for Windows; Terminal for Mac or Linux) and navigate to the directory/folder where the adb and fastboot utilities are located:

+ for Windows, you need to start-up a Windows Command Prompt (DOS window) and type the following (for example, assuming that your adb / fastboot files are in the c:\sdk-tools folder):

Code:

cd c:\sdk-tools

+ for Mac/Linux, start-up a Terminal session and type the following (for example, assuming that your adb / fastboot files are in the sdk-tools folder):

Code:

cd sdk-tools

E. next, boot your phone into fastboot mode (press and hold both the volume-UP and volume-DOWN buttons and then press the power button)

F. if you are using Windows, install the appropriate Samsung USB drivers

http://androidforums.com/galaxy-nexus-all-things-root/470831-big-how-thread-under-construction-check-back-soon.html#post3711706

G. let's verify that fastboot can "see" your device

note: for simplicity's sake, I'm using the generic "fastboot" command name here; your fastboot utility might actually be named:

+ for Windows: fastboot.exe or fastboot-windows.exe
+ for Linux: fastboot or fastboot-linux
+ for Mac: fastboot for fastboot-mac

- from your PC, enter the following to verify that the fastboot utility can see your phone:

For MS/Windows:

Code:

fastboot devices        (list connected devices)

For Mac/Linux:

Code:

./fastboot devices        (list connected devices)

- you should see something similar to this:

Code:

sdk-tools> fastboot devices
<device serial #>   fastboot

J. next, you'll re-lock the bootloader

For MS/Windows:

Code:

fastboot oem lock            (re-lock the bootloader)

For Mac/Linux:

Code:

./fastboot oem lock            (lock the bootloader)

J. That's it, your bootloader should now be re-locked and you are ready for your next step. You phone should still be in fastboot mode at this point.

If you simply wanted to re-lock the bootloader and now want to reboot your phone, you can issue a "fastboot reboot" (for Windows) or "./fastboot reboot" (for Mac/Linux) to reboot the device normally.

If you are not ready to reboot, but need to do other fastboot-related operations, then your phone is still in fastboot mode and ready for you.

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