[GUIDE] How to lock unlocked/relocked bootloader (and fully restore device) - Huawei P9 Plus Guides, News, & Discussion

Hi all, this is my first post on the XDA. I am sorry if this is a duplicate post, but it seems that no one have posted this yet. Please beware that this method will completely erase the device, since it involves reflashing via original UPDATE.APP.
First of all, you need the bootloader unlock code. You can get it from huawei's website or DC-unlocker. Personally, I use android app DC-unlocker here on play store (it is cheaper, only 1 EUR).
Then, you need the stock ROM UPDATE.APP. If you have unlocked bootloader, chances that you also have TWRP installed. Boot to TWRP, and transfer the UPDATE.APP to the dload folder of internal storage via TWRP's built-in MTP support. Alternatively, if you don't have TWRP, you may flash the TWRP first, or copy the UPDATE.APP to an external SD card (also the same dload folder). Make sure the SD card is formatted as FAT32 (I've not tried exFAT/ext4 yet). Note that HW folder is not strictly required (optional).
After you've copied the UPDATE.APP, you must flash the stock EMUI recovery (also via fastboot). You can get it from the UPDATE.APP mentioned above using this windows software here. If you use the Huawei Update Extractor, use profile "Unknown (worstenbrood)". Then right-click, extract the RECOVERY.img (not RECOVERY2.img). You may flash the extracted RECOVERY.img via fastboot, e.g.:
Code:
fastboot flash recovery RECOVERY.img
Make sure the bootloader is in "unlocked" state.
Do a reboot via fastboot. Immediately after the "your device cannot be trusted" screen appears, hold the volume up button to enter the e-recovery. Then press shut down on the e-recovery screen.
Last step, press and hold volume up and down, along with power button. The device will start flashing the UPDATE.APP. After it's done, the device will be reverted to brand new factory state, and the bootloader state will become "locked", not relocked.
Tested and working on my VIE-L29 C636 using the B170 UPDATE.APP.

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Ho, how can i check if bootloader status is locked or relocked ?
Thank you

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Fil76 said:
Ho, how can i check if bootloader status is locked or relocked ?
Thank you
Click to expand...
Click to collapse
Start your phone in fastboot mode.
Sent from my HUAWEI VIE-L29 using XDA Labs

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Mostar088 said:
Start your phone in fastboot mode.
Sent from my HUAWEI VIE-L29 using XDA Labs
Click to expand...
Click to collapse
thank you
Phone lock
frp unlock

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Great post
Thank you

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my phone enable oem unlock but FRPlock still lock ..ican't unlock bootloaderor flash everything what happen on my P9+

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ccgchhun said:
my phone enable oem unlock but FRPlock still lock ..ican't unlock bootloaderor flash everything what happen on my P9+
Click to expand...
Click to collapse
First, to enable bootloader unlock, you must unlock FRP first. This can be done from developer options -> enable OEM unlock. Now, if you can't boot to the OS and have the default recovery (not TWRP) installed, you can try to factory reset the device.
If you still unable to boot, try to flash a default firmware, complete with it's HW folder, by using a TF/MicroSD card. Format your SD card as FAT32, and copy those firmware files to a folder called 'dload' on the root of the SD card. Then, insert the SD card to the device, and press these 3 buttons simultaneously : Power + Vol Up + Vol Down. Your device should begin to flash itself.

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Worked.

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My P9+ having issue always restart. How to 'relock' back my phone?
I check using fastboot my phone:
Phone unlocked
frp lock

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mbursi said:
My P9+ having issue always restart. How to 'relock' back my phone?
I check using fastboot my phone:
Phone unlocked
frp lock
Click to expand...
Click to collapse
Flash full stock firmware and it will lock.
Sent from my VIE-L29 using XDA Labs

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Mostar088 said:
Flash full stock firmware and it will lock.
Click to expand...
Click to collapse
If you have TWRP, don't forget to flash the stock recovery first (guide can be found at the top of this thread)

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Mostar088 said:
Flash full stock firmware and it will lock.
Sent from my VIE-L29 using XDA Labs
Click to expand...
Click to collapse
After flash full stock it's work. My Phone lock.
But, after restart it's unlocked again.
Do you encounter this before?

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HI I have relocked my device but when I do a factory reset it I get stuck in the encrytion loop (i put in my password to decrypt it says it still needs to reset) but when phone reboots after reset it says the same thing (data encryption...) any idea? thanks J

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P9+
Mostar088 said:
Flash full stock firmware and it will lock.
Sent from my VIE-L29 using XDA Labs
Click to expand...
Click to collapse
After Flash stock firmware, the bootloader is lock..but, after restart it's unlock again.
Any idea?

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Use three button recovery metod from shut down, and see to it that you keep all three buttons pushed until it's actually installing. But that may not be enough to get the phone 100% restored, mine didn't get totally restored until I made an update for the same rom from inside the service menu when the phone is turned on. Finally I got the "success" message and all warnings went away.

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Phone locked frp lock
jnakoda said:
If you have TWRP, don't forget to flash the stock recovery first (guide can be found at the top of this thread)
Click to expand...
Click to collapse
pls i want fix my phone
PHONE LOCKED
FRP LOCK
problem: no unlock bootloader
give me this error FAILED (remote: Command not allowed)
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jnakoda said:
Hi all, this is my first post on the XDA. I am sorry if this is a duplicate post, but it seems that no one have posted this yet. Please beware that this method will completely erase the device, since it involves reflashing via original UPDATE.APP.
First of all, you need the bootloader unlock code. You can get it from huawei's website or DC-unlocker. Personally, I use android app DC-unlocker here on play store (it is cheaper, only 1 EUR).
Then, you need the stock ROM UPDATE.APP. If you have unlocked bootloader, chances that you also have TWRP installed. Boot to TWRP, and transfer the UPDATE.APP to the dload folder of internal storage via TWRP's built-in MTP support. Alternatively, if you don't have TWRP, you may flash the TWRP first, or copy the UPDATE.APP to an external SD card (also the same dload folder). Make sure the SD card is formatted as FAT32 (I've not tried exFAT/ext4 yet). Note that HW folder is not strictly required (optional).
After you've copied the UPDATE.APP, you must flash the stock EMUI recovery (also via fastboot). You can get it from the UPDATE.APP mentioned above using this windows software here. If you use the Huawei Update Extractor, use profile "Unknown (worstenbrood)". Then right-click, extract the RECOVERY.img (not RECOVERY2.img). You may flash the extracted RECOVERY.img via fastboot, e.g.:
Code:
fastboot flash recovery RECOVERY.img
Make sure the bootloader is in "unlocked" state.
Do a reboot via fastboot. Immediately after the "your device cannot be trusted" screen appears, hold the volume up button to enter the e-recovery. Then press shut down on the e-recovery screen.
Last step, press and hold volume up and down, along with power button. The device will start flashing the UPDATE.APP. After it's done, the device will be reverted to brand new factory state, and the bootloader state will become "locked", not relocked.
Tested and working on my VIE-L29 C636 using the B170 UPDATE.APP.
Click to expand...
Click to collapse
May i know how do you RECOVERY.img via fastboot?
Is it placing the RECOVERY.img file in the dload folder and then press the up+down+power button?

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moony2017 said:
pls i want fix my phone
PHONE LOCKED
FRP LOCK
problem: no unlock bootloader
give me this error FAILED (remote: Command not allowed)
Click to expand...
Click to collapse
You have to do FRP unlock first. If you somehow cannot boot to the OS, try to reset user data first.

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prismfire said:
Make sure the bootloader is in "unlocked" state.
Do a reboot via fastboot. Immediately after the "your device cannot be trusted" screen appears, hold the volume up button to enter the e-recovery. Then press shut down on the e-recovery screen.
Last step, press and hold volume up and down, along with power button. The device will start flashing the UPDATE.APP. After it's done, the device will be reverted to brand new factory state, and the bootloader state will become "locked", not relocked.
Tested and working on my VIE-L29 C636 using the B170 UPDATE.APP.
May i know how do you RECOVERY.img via fastboot?
Is it placing the RECOVERY.img file in the dload folder and then press the up+down+power button?
Click to expand...
Click to collapse
Just use "fastboot flash recovery recovery.img".

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Hi jnakoda, thank you for this useful guide. I followed your steps and my phone is locked now, but it says FRP unlocked.
How can I lock a FRP? I need to do this because of warranty.
Thank you in advance.