If you want, I can now:

Ensure your battery is charged to at least before starting.

Reliability and endurance:

When you extract a 6531e_flash.bin file (size exactly 4,194,304 bytes), it is rarely just raw code. Here is the typical layout observed in production units:

Usually, the center button, call button, or a combination of * and # must be held while inserting the USB cable to initiate communication.