Bootloader Error

Does anyone know why the Pixhawk 2.4.8 can’t be read by my laptop? It has a red light in the B/E (referring to the manual, it indicates a bootloader error) and a solid white light in the LED indicator. How can I fix it?

You can first check if this FC has been loaded with proper version of firmware.
As the hardware is kind of historical, perhaps can start with trying to upload an earlier version of firmware to see if it can works better.