While the reason of their public availability is unknown, our best guess is that To make any use of this mode, users must get hold of OEM-signed programmers, which seem to be publicly available for various such devices. All of these guides make use of Emergency Download Mode (EDL), an alternate boot-mode of the Qualcomm Boot ROM (Primary Bootloader). There are many guides across the Internet for ‘unbricking’ Qualcomm-based mobile devices.