I want to flash TWRP & SuperSU to take a backup, but I read that if you flash TWRP with a locked bootloader it would brick my device & wipe my data, now that would just defeat the purpose. How do I determine if my device bootloader is locked or not?

I have enabled developer options, enabled USB Debugging, there is a option in the menu 'OEM Unlock', what does it do? Does it wipe data?

Device - Samsung Galaxy-J700F


to just answer your question, and without needing any software, you can start your phone (or tablet) in bootloader mode by holding the volume key and the power key from an OFF state. the software will then tell you the info you want.

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    Putting it in Download Mode I get The Following ODIN MODE, DOWNLOAD SPEED : FAST, PRODUCT NAME : SM-J700F, CURRENT BINARY : SAMSUNG OFFICIAL, SYSTEM STATUS : OFFICIAL, SECURE DOWNLOAD : ENABLED, WARRANTY VOID : 0 (0×0000), RP SWREV : B:4 K:0 S:1, FRP LOCK : OFF What does all of this mean, it says nothing about the bootloader state. – Guest1234 Jun 14 '18 at 8:53

I'm not sure if this directly answers your question. However, here's what I can add:

  1. Android phones should display a warning at bootup, informing you that your device's bootloader is unlocked and that it cannot be trusted. This is the default behavior for all modern Android phones. If you do not see any such warning, then your device is most likely still locked.

  2. The OEM unlock setting in developer options should fade off (and get disabled) when the bootloader is unlocked. Here's a screenshot of how it looks on my phone:

Android OEM unlocking

So, since both of the above show that your device is not unlocked, I will go with it.

And AFAIK, trying to flash TWRP on a locked bootloader would actually fail, instead of bricking the device. That's all the purpose of a locked bootloader - to avoid tampering of the system.

You will actually have to look for a way to backup your data without the bootloader unlock. Since, if you decide to unlock it now, all data will be erased. I believe XDA-Developers forum will be a good place to look for information.

Edit: Try if you can boot the TWRP, instead of flashing. And then flash SuperSU from TWRP. Things like these were possible on older devices.

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    How to boot TWRP instead of flashing? – Guest1234 Jun 14 '18 at 8:57
  • Ideally, fastboot boot recovery.img But, yes, same question from comment on your question. Does Samsung talk with fastboot? Probably not. So, I'm sorry, it won't work. – singhnsk Jun 14 '18 at 9:04
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    I forgot to mention that my device is not tied to any carrier, this link from izzy says that samsung does not lock bootloaders, only some carriers do that, is this true? android.stackexchange.com/q/187873/16575 – Guest1234 Jun 14 '18 at 9:26
  • No that's not true. Carriers may make bootloaders on some branded phones as non unlockable. All Samusng phones come with a locked bootloader. Some are unlockable via a simple unlock command; while others require the user to have an encrypted unlock key to unlock it. That is why in my answer I mentioned that Android phone with unlocked bootloader will show the warning. – singhnsk Jun 14 '18 at 9:33
  • If I flash CF-AutoRoot, would that work? What about kingroot? are they safe to use? – Guest1234 Jun 14 '18 at 9:37

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