Motorola Unlock Bootloader |top| Here

This requires a PC, a USB cable, and a lot of patience.

The bootloader is the software that runs every time your phone starts up. It instructs the phone on how to boot its operating system and ensures that only "signed" (official) software is loaded. By default, Motorola locks this to prevent unauthorized modifications. Unlocking it allows you to run unsigned code, which is necessary for most advanced customizations. motorola unlock bootloader