Android Bootloaders and Unlocking
What is a Bootloader?
- Hard boot : When Power On Self Test (POST) is performed, where every component of CUP is checked for errors and malfunctions.
- Soft boot : When POST is skipped in order to minimize booting time.
Booting is complete when the normal, operative, runtime environment (operating system) is attained.
Since bootloaders directly operate the hardware, they are device specific. Every mother-board and every Mobile Phone has its own bootloader.
Since all the smart phones use some operating system (called as ROM in case of android phones) they need booting and in tern a boot loader. In case of android phones most manufacturers ship their phones with their own version of android and hardware configuration. So every android has its own bootloader. Now manufacturers want their customers to use their own supplied ROM for their device for many reasons so they lock the bootloader i.e configure it to load only shipped ROM (stock ROM).
Why is Bootloader Locked?
Android is open source and customizable still manufacturers lock the bootloader to prevent their customers from using other ROMs. For reasons like
- Avoiding loss of device specific features like S pen in case of Note devices or Air gestures in case of Galaxy S4, S5 etc. Custom ROMs may or may not provide these features.
- Avoiding the damage to the device which may be caused by use of tweaks like over-clock, fast charge, etc.
Unlocking the bootloader voids the warranty.
Why To Unlock Bootloader On Android Devices?
There may be some risks when you try to unlock the bootloader but if you follow the instructions carefully it is very unlikely to brick the phone plus the benefits are much more. By unlocking the bootloader you’ll be able to
- Flash (install) a custom ROM.
- Flash a custom recovery.
- Root your phone via custom recovery.
- Even dual boot your phone.
How To Unlock Bootloader On Nexus Android Devices:
The procedure for unlocking the bootloader varies with the manufacturer and device. Google Nexus phones are simplest to unlock procedure is given below
- The first step is download and install Android SDK as instructed in this post.
- Once you are done with downloading and installing SDK, turn off your device and boot in bootloader mode:
- On Nexus One, press and hold the power button and trackball.
- On Nexus S, press and hold the volume-up and power buttons.
- On Galaxy Nexus, press and hold volume-up, volume-down and power buttons.
- On Nexus 4, press and hold volume-down and power buttons.
- On Nexus 7, press and hold volume-down and power buttons.
- On Nexus 10, press and hold volume-up, volume-down and power buttons.
- Connect your device to your PC via USB and wait till any drivers are installed, which should happen automatically.
- Now go to command prompt / terminal interface on your computer and type following command:
fastboot oem unlock
- Once this is done, your phone will show a screen that will prompt you regarding unlocking bootloader. Read through the instructions carefully and confirm by pressing volume up button followed by the power button.
There you go! You now have your bootloader on your Nexus Android device unlocked.
Now the procedure for unlocking bootloaders on Nexus devices is easy because Google itself expects its customers to do so. But in case of others (like Samsung HTC, LG, Sony) it not that easy and would have been impossible without hackers and developers who make the cracks and patches to do the task. Now if you have different phone, you can find the procedure for unlocking the bootloader for your device on xda-developers.
Hope you liked the post.