[GUIDE] How to unlock bootloader for your Qualcomm based Nokia Android Phone

This article is a backup of original XDA topic because original topic violates the rule of XDA – any kind of selling is prohibited.
本文是XDA原帖的备份，因为原帖违反了XDA相关规定——禁止以任何形式在论坛贩卖、出售。
中文版教程请看这里

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UNLOCK BOOTLOADER WILL VOID YOUR WARRANTY AND ERASE DATA ONCE UNLOCKED, DO IT AT YOUR OWN RISK

And please DO NOT DUPLICATE this topic to any other Nokia forum.
You can just share the link to this guide, but DO NOT COPY this guide without my permission. Because the procedure could change depends on HMD’s attitude and any other incoming changes, be aware of that.

Quote:
Alternate method is still testing on all FIH-made phones.

I strongly recommend you to install OST LA from there: https://drive.google.com/open?id=1n9…v8TjfeLc64AcYA

To install it properly, extract this pack and right click on setup.bat, run it with administrator privileges.

Wow, this is a great breakthrough of Nokia Android development.

This guide should work on Nokia 2, 5, 6 (2017), 6 (2018), 7, 7+, 8, 8 Sirocco (Until March 27th) and Nokia X6 (Until May 29th).

For Nokia 1 and 3, check related guide on Nokia 3 forum.

Alternate unlock method for Nokia 2, 5, 6 (2017), 7 and 8 is testing. Will release once widely confirmed.

UPDATE: Now you can use this script to unlock the bootloader easily.
https://github.com/HikariCalyx/OSTRemote/releases/tag/1.0.2.unlocktool
To users who are sensitive about trojan / virus / spyware report of packed script with bat2exe, you can review and use this source code instead: https://github.com/HikariCalyx/OSTRemote/blob/master/FlashingScript/qualcomm_unlock_script_en.bat

1. Backup all the data you have to either your PC or Cloud Drive. For Nokia 5 and 6 users with custom recovery, if you want to do data backup before unlocking, remove the lockscreen password before proceed.

2. Get your Phone’s model, Codename, IMEI, MEID and Serial Number. These are important for unlocking.

Take my Nokia 6 (2017) for example:
Model: Nokia 6 TA-1000 (Codename D1C)
IMEI and MEID can be obtained by dial *#06#.
Serial Number can be found in “Settings” – “About Phone” – “System Status”, or dial *#*#227#*#*. For example, Nokia 6 China Variant’s Serial Number starts from D1C.

3. Buy the unlock code service request from the link above. (Sorry but I still need to figure out how to charge from users outside China)

If you do not trust me to use your IMEI, MEID and SN, then stop right here.

4. Turn on “Allow OEM Unlocking” in Development Settings, just in case.

5. Reboot to download (fastboot) mode. You should be familiar with how to enter download mode if you’ve tried OST LA.

WARNING! WARNING! WARNING!
IF YOU WANT TO KEEP YOUR PHONE IN WARRANTY, STOP RIGHT HERE!
IF YOU DON’T CARE ABOUT THAT, GO AHEAD.

6. Type these commands with your own fastboot:

Code:
fastboot flash unlock D:\unlock.bin
fastboot flashing unlock_critical
If you’re using the phone with AB partition scheme like Nokia 6 (2018), you’ll see a prompt that needs your confirmation.

<!>

By unlocking the bootloader, you will be
able to install custom operating system on
this phone. A custom OS is not subject to
the same level of testing as the original
OS, and can cause your phone and installed
applications to stop working properly.

Software integrity cannot be guaranteed with
a custom OS, so any data stored on the phone
while the bootloader is unlocked may be at
risk.
To prevent unathorized access to your
personal data, unlocking the bootloader will
also delete all personal data on your phone.

Press the Volume keys to select whether to
unlock the bootloader, then the Power Button
to continue.

_____________________________________________
DO NOT UNLOCK THE BOOTLOADER
_____________________________________________
UNLOCK THE BOOTLOADER
_____________________________________________

If you’ve flashed custom recovery before, the recovery will prompt you to type decrypt password, ignore that. Then tap 清除(Wipe) – 格式化 Data 分区 (Format Data Partition), type yes to proceed, then reboot your phone.

However, if you’re running August 2018 Security Update (Or September 2018 Update), the unlock key can’t be accepted and workaround required. (So you’d better not to install August and September update)
Currently:
For Nokia 2 & 5 & 6: Install July 2018 OTA package in stock recovery
For Nokia 7 plus: Install early Android Pie Preview to unlock (B2N-3050)
Any other models with AB partition scheme: Switch to another slot with following commands:
fastboot getvar current-slot
(If current slot is B)
fastboot --set-active=_a
(If current slot is A)
fastboot --set-active=_b
fastboot reboot-bootloader

Then try to unlock it again.

7. After your phone rebooted and done factory reset, enter Download mode again, then type these commands:
Code:
fastboot flash unlock D:\unlock.bin
fastboot oem unlock-go
You need to confirm again, If you’re using the phone with AB partition scheme.

8. Now your phone will reboot with bootloader unlocked, with the prompt like this:

Quote:
Your device has been unlocker and cann’t be trusted.
ID: D1CXXXXXXXXXXXXX

Your device will reboot in 5 seconds.

Or looks like this:

Quote:
Your device software can’t be checked for corruption. Please lock the booloader.
ID: D1CXXXXXXXXXXXXX

Your device will be continue in 5 seconds.

Or:

[!]

Your device software can’t be checked
for corruption. Please lock the
bootloader.

Visit this link on another device:
g.co/ABH

PRESS POWER TO CONTINUE
Your device will continue in 5 seconds.

ID: C1NXXXXXXXXXXXXX

8. The phone will enter the recovery to erase data.

If you’ve flashed custom recovery before, the recovery will prompt you to type decrypt password, ignore that. Then tap 清除(Wipe) – 格式化 Data 分区 (Format Data Partition), type yes to proceed, then reboot your phone.

9. Your phone will enter the system again.

For Nokia 6 (2018), Nokia 7, Nokia 7+, Nokia 8 and Nokia 8 Sirocco users: After your phone get bootloader unlocked, and you’re able to get original boot, you can root your phone with Magisk.

Special thanks:

@the_laser for providing unlock method support
@heineken78 for hints and providing correctly patched OST LA