Also I managed Brick mini NVR but I was lucky because update file from this forum.
Copy the files to formated FAT32 usb. Insert the USB into the NVR and turn it on.
If you NVR with another firmware update, use the correct files but the process will be about the same
Sorry bad English and the bad video quality
http://uloz.to/xDiyaSnR/repair-broken-xvision-xrn0808e-with-usb-zip
9FTofvjmthk video will later be active / my upload is very slow /