There are a few devices on which the bootloader can be unlocked without the need of a PC and fastboot command sets. For example, many Samsung devices can be bootloader unlocked by going to device Settings>About Phone and tapping Build Number 7 times until Developer Options is enabled. In Developer Options, enabling the OEM Unlock option will unlock the bootloader, thus disabling the layer of protection which restricts flashing of certain device partitions. Other than Samsung, there are some device OEMs and models which also allow bootloader unlocking in this manner. However, on most devices, in addition to enabling OEM Unlock, fastboot mode must be initiated, device and PC synced with a cable, and a command line or command set must be executed.

To see if your particular device can be bootloader unlocked without a PC, visit xda-developers com and search the forums and threads relating to your device model.




What's an OEM unlock in Android?

Despite what you've been told, rest assured that an OEM unlock will not, in and of itself, cause damage to your device. If you go to Settings>About Phone & tap Build Number 7 times (assuming you are running Android 5.0 or later), a hidden menu called Developer Options will appear. In this menu, you will find (unless the manufacturer blocks it) an option called OEM UNLOCKING. Enabling this feature makes absolutely no change at all to your device, except for giving you the option to manually unlock your bootloader. To reiterate, this does not unlock your bootloader, but allows you to manually unlock it via a tethered command prompt if you so choose.

So, let's say you enabled OEM UNLOCKING and then manually unlocked your bootloader using a tethered fastboot mode command line. (I'll skip over the actual procedure, which differs from device to device. ) So now that your bootloader is unlocked, what changes? Well as far as your Android OS goes, nothing changes. Unlocking the bootloader removes a layer of protection which allows your /boot, /recovery, /system, /modem & other partitions to be flashed. This is not rooting and not the same as rooting. Therefore, an unlocked bootloader does not alter your /system partition or your Android OS directly, as others have erroneously stated. But, you can now flash your device with a custom recovery which will allow you to install a custom ROM, a custom kernel, or flash a root script to your stock Android OS, among many other things. Bootloader unlocking & rooting are two separate & distinct procedures and the two are not dependent on one another. In other words you can fully root a device with a locked bootloader, just as you can have an unlocked bootloader and have a non-rooted device. Of course, to have full customization options, rooting and bootloader unlocking are preferred.

As far as your warranty goes, you can void it without unlocking the bootloader. Again, you can achieve full root without OEM UNLOCKING, which can void your warranty. Just as a bootloader can be unlocked, it can be relocked. Same with rooting. It can be removed as well. Most devices which have been modified and/or OEM unlocked can be restored to stock factory condition, with no trace that any modifications were ever made. I've done this very thing to a number of my own devices whenever a warranty needed to be used.



Is it necessary to unlock bootloader before rooting Android phones?

Depends on your phone. Older versions of android upto android 5(lollipop) had several vulnerabilities which could be exploited to get root access using apps like Kingroot etc. These apps would use certain hacking techniques to write su binary to the System Partition which was supposed to be Read Only. This would give root access without unlocking bootloader. However most of these vulnerabilities were patched up in later versions of android so in newer Android phones rooting can only be done officially by unlocking bootloader, flashing a custom recovery and then flashing the System Partition with su binary in zip format or flashing a boot image patched with magisk module. Also an unlocked bootloader allows you to flash custom ROMs of your choice since there is no signature verification done by bootloader



How do I check whether bootloader is unlocked or not?

All the answers here apply for devices other than MTK (Mediatek Devices). For MTK, neither the dialer option nor “fastboot oem device-info” works.

First, install ADB & Fastboot on the computer. Then open cmd from the search bar. Connect mobile with USB to the computer and allow USB debugging (developer options must be enabled). Type “adb devices” (all commands without quotes obviously).

If the device name shows up, good to go. Otherwise, follow the above steps correctly.

Switch off mobile. Press Volume down and power button simultaneously.

Now pressing up or down volume key enter recovery mode (fastboot mode). [Writing simply fastboot devices without entering fastboot mode doesn’t work.]

Now type “fastboot devices” in cmd. If the device name shows up, Voila!

Next type “fastboot getvar unlocked”. It will return unlocked: yes or no.

Another simple way (without pc) to find out if OEM is locked is to visit developer options and OEM unlocking will have an option to unlock it.

But if it is unlocked, the button will be greyed out showing bootloader is already unlocked.


How do I unlock a bootloader without a PC and without a root in Android?

Without knowing what Device you have no one can answer your question properly.

I am only answering it to clear up some very wrong information the 2 answers I did read gave you.

  1. Unlocking your bootloader will not void the warranty or make it vulnerable but flashing none signed files with it will put the warranty in jeopardy, depending on what country you are in.
  2. An unlocked bootloader is not a prerequisite to root it is possible to root some devices with a locked bootloader.
  3. Some answers talk about Fastboot that is only for some phone makes and another reason I said the question can not be properly answered.

I have a Samsung S9+ sold in my country by Samsung, with an unlocked bootloader. It has a warranty of 2 years, but if I root it and trip knox the warranty still has to be honored if the problem is hardware and not the firmware I may install.

I would ask your question again mentioning what phone you have and you will get better answers than the BS I read.

I do agree that without a PC what can be done with your unlocked bootloader will not be as easy as with one.


What are the main differences between rooting and unlocking a bootloader?

Bootloader
Having an unlocked bootloader enables you to flash custom roms, custom kernels, recoveries and so on. (custom roms etc. mean modified versions of android).
A locked bootloader locks write access to several partitions like the system partition. This is the reason why rooting is not able without unlocked bootloader. Rooting needs write access to the system partition (for storing the superuser binary and
the superuser app). Without unlocked bootloader, only a temporary half-root can be achieved.

Root
Rooting a device is a method to gain full access to the operating system. With root you can do all the administrative stuff like write to locations normally restricted to the system, delete preinstalled apps, overclock CPU and
customize your device deeper.
Root enhances your privileges and you are able to control almost anything inside of your rom.
The rooting, however, affects ONLY your operating system (Android).


How do I unlock bootloaders on Samsung phones?

Before you try to install any custom ROM on your device, you need to unlock the phone’s bootloader, which is a code executed before any OS (operating system) launch. The notion of a bootloader is unanimous to all operating systems worldwide and includes systems running on your personal computers, laptops, tablets, smartphones, smart watches and basically everything that has OS on it

HTC website has a section for developers where you can grab SDK; you just need to find your phone’s model. Samsung website does not offer such luxury, Sony Mobile website offers a section for users looking to unlock their Sony’s bootloader.

  • So, For Samsung Devices How to unlock Bootloader?

To unlock the boot loader you need to have the ADT with all the packages installed and configured.

Later once the configuration is done properly then you can connect your device and enable USB Debugging under the options.

  1. Download Modaco’s Superboot files and save them to your computer.
  2. Once downloaded, extract it by right clicking and extract all.
  3. On your phone, click on Settings > Developer Options > Turn USB Debugging On.
  4. Plug the device in to your computer via USB cable.
  5. Open the superboot folder that we just extracted (until you see the folder with fastboot-windows inside it), then hold the shift key down on your computer and right click any blank area.
  6. Now, select open command window here.
  7. In the command prompt, type the following with hitting enter at the end of each line.

adb-windows reboot bootloader (and wait for the device to reboot) fastboot-windows oem unlock *If it gets stuck at waiting for device here, download and install PDANet on your computer, once installed, unplug then plug the device back in and see if that fixes it.

Once it runs the device should display a screen asking you if you are sure. Click yes using the volume buttons. The device will go back to the bootloader screen but say unlocked at the bottom.

Note: please take up the backup if not done properly you will lose all the data...

This process some samsung phones only.. not for all..