For anyone who wants to enable mouse control for android, but keeps getting the failed to connect message when reaching 20% complete on loading after starting their first “Control from PC mode” through a USB connection:
When I encountered this problem, I went through all the provided instructions, including turning on USB debugging, enabling “always allow use” of my android through my computer, downloading the android usb driver for PC (for me through developer.samsung.com/) and then checking that it was working properly (driver talent app)…
And it STILL wouldnt work, and keep aborting at around 20% complete…
…HOWEVER
I restarted my phone and computer and the programs in different ways multiple times, and kept replugging my phone through USB … and to my big, big surprise – SUDDENLY IT COMPLETED THE PC MODE CONNECTION ESTABLISHMENT!
And now the program works perfectly with my mouse and keyboard.
So just FYI, this was my story of how I resolved this connection issue.