Before everything I've recommend to make a full backup of your stock firmware check this post.
- USB cable
- Basic knowledge of command-promt commands
- ADB/Fastboot minimal drivers - download
- Moto E4 drivers - download
1. First prepare Moto E4 to work with adb
2. Go to settings -> About phone -> tap 7times on build.number until appeared message You're now a developer!.
3. Then go back to root of settings and at the end needs to be unlocked new menu Developer options then open it.
4. Locate Oem unlocking and enable.
5. Locate Usb debugging and enable.
6. Plug USB cord to PC and phone.
7. In PC open command-promnt (you can easy open with run/windows button+R/ and type cmd).
8. Type adb devices and on phone screen needs to be appear message Allow usb debugging.
if showing something like z23436556 and attached you're on right way.
9. Type adb reboot bootloader (phone will rebooted into bootloader).
if on phone screen appeared on left bottom corner fastboot mode >> you're on fastboot mode for unlocking bootloader proccess.
10.Type fastboot devices ( if showing blank you need to install drivers from device manager for thus follow these steps).
- devicemanager can be accessed from run command type devmgmt.msc
- locate Android on other devices section
- then right click and Update driver software... -> browse my computer for driver software -> let me pick from a device list of device drivers on my computer -> Android device - > Motorola ADB interface and confirm installion of driver
11.Type in cmd fastboot oem unlock.
12. On Moto E4 screen will appear message to confirm unlocking of bootloader press VOL UP for confirmation.
13. If unlocking proccess started you will see something like this on command-promt:
- Start unlock flow
- Total time.31.600s
14.If everything goes good on Moto E4 screen will appear recovery, bootloader, reboot.
15.That's it Moto E4 bootloader was unlocked without oem key providing!
If you try to boot with unlocked bootloader you can't boot it you need to flash kernel which works with unlocked bootloader therefore you can use stock unlocked rom.