I wrote a tutorial for myself on this so that I would save myself time every time I wanted to update the firmware. I updated it in November 2019 and then decided to sit on it for a few days to "let it ripen" so to speak before reviewing it but then I forgot all about it and 7 months went by!!!
Reading of your problems reminded me of it and so I've attached it here. Hopefully it helps.
Comments and feedback welcome.
It seems as though you have either not programmed the arduino to act as an ISP correctly or there is a wiring error between the arduino and the QCX.