You can find step-by-step visuals in the MXQ S805 Install Guides on YouTube , which cover various firmware upgrades .
: This indicates a bad USB connection or an incorrect USB port. Use a shorter cable and try different ports on your PC. Mxq Amlogic S805 Android 5.1.1 Lollipop Download
because the official manufacturer rarely released an update beyond Android 4.4 KitKat for this specific hardware. Firmware Download & Tools You can find step-by-step visuals in the MXQ