Done on Samsung S9 smartphone.
1) Need OTG-USB dongle - plugs into phone and USB Programming Cable. Using a USB Female-Female connector w/ Phone charge cord as a cheat, doesn't work. Hopefully you got the dongle with your phone.
2) Playstore, add "Serial USB Terminal" by Kai Morich - it works for me
3) Playstore - Search Bafang BBSHD, see "Speeed Configuration Tool" add that.
4) Plug in all Cords to Bafang Green Controller port.
5) Open "Serial USB Terminal", should recognize Programming Cord. At top, next to TERMINAL - Click Cable Connector Icon then you see connection complete
6) Open "Speeed" app and turn it Sideways for Landscape viewing. This is so you see the BLUE Connect button- push that.
Usually it connects and it works like the Laptop Programs you see for Bafang Programming. Google Bafang Programming and research articles there. Easy to burn out a controller if programmed wrong and you run high amps with a bogged down motor.
"Low Gear & Fast Motor Spin = long Controller Life".
Of course this Reprogramming voids any warranty. Good luck