Hi friend, 
Sorry for the inconvenience to you. Because there may be some android 6.0 boxes from our last shippment mixed in the android 7.1 version at the amazon warehouse.  
This is our android 7.1 firmware and the flashing steps. 
This is the firmware, please download it from MEGA:

This is the video that show you how to flash it:

If there is any problem please feel free to contact us again!

Best Regards,
Pendoo customer service team