ohhh I understand..... I need to add the chmod command in a file that runs at boot because:  

       Setting permis‐
       sions with "chmod" is not permanent... they will be reset  after
       reboot or replugging the scanner.

so then it would be to add
     chmod 770 /dev/bus/usb/*

to /etc/rc.local .

Or perhaps the kernel is claiming the scanner?

       Libusb  can  only access your scanner if it's not claimed by the kernel
       scanner driver. If you want to use libusb,  unload  the  kernel  driver
       (e.g. rmmod scanner under Linux) or disable the driver when compiling a
       new kernel.