Download Android KitKat stock firmware for Minix Neo X8-H Plus TV Box from here or here. Download another Minix firmware from here. To flash the firmware on this box from PC via AMLogic USB Burning Tool provided in the archive read this article.
Archive name: X8H_PLUS_stock
Archive size: 405 MB
Image file name: aml_upgrade_package_20141122.img
Support: Amlogic S812
Release date: 30/11/2014