The phone shows no signs of life, a black screen, and does not respond to standard button combinations.

Double-check your test point. If the pins aren't shorted correctly while plugging in the USB cable, the COM 1.0 port will not trigger.

This is a modified cable that re-wires the standard USB connection to enter a short-circuit diagnostic mode on the phone, enabling deep-level access for repair. When using this cable, your device will be automatically recognized by the PC as a "Huawei USB COM 1.0" port in Device Manager.

Run Command Prompt as Administrator and execute the following command to disable driver signature enforcement: bcdedit /set testsigning on After entering the command, restart your PC for the change to take effect.