Factory Reset an Android 7 Nexus 5x Phone with No Root or Unlocked bootloader I just purchased a nexus 5x on ebay and there is a PIN on the phone and I need to factory reset this. I am able to get to the black screen mode on bootup using volume down and power button. Fastboot command detects it, but fastboot erase userdata fails as it throws and error saying: "device is locked". 

How can I factory reset and Android 7 Nexus 5x Phone with a locked bootloader?
A master reset will erase all data stored on the device.

This type of reset should only be used as a last resort after all other troubleshooting steps have been exhausted. It is highly recommended that you complete a backup of the device information and disable Device Protection before proceeding with the steps in this tutorial.

With the device turned off, press and hold the Volume down key.

Note: If Device Protection is not disabled, the login credentials for the Google account currently associated with the device will be needed to set up the device after the reset.

With the Volume down key held down, press and hold the Power key.

Release both keys when the Android screen appears.

Use the Volume keys to scroll to Recovery mode.

Press the Power key to select Recovery mode.

When the No command message appears, press and hold the Power key.

While holding the Power key, press and release the Volume Up key.

Note: Release the Power key when the Android Recovery screen appears.

Press the Volume down key to scroll to Wipe data/factory reset.

With Wipe data/factory reset highlighted, press the Power key.

Press the Volume down key to scroll to Yes, then press the Power key.

Once the wipe is complete, with Reboot system now highlighted, press the Power key.

The device will restart.