Root BPI-M64 Android

Hello,

How do I get root access on the Android image for the BPI-M64?
I've made some progress by running these commands from ADB shell:

mount -o rw,remount,rw /system
cd /system/bin
chown root:root su
chmod 6755 su

This allows me to use 'su' command on terminal app but apps like SuperSu say I do not have root

Any ideas?