Hello.
Fully charge phone's battery by using external charger (at least to 4.1V), connect the phone directly to PC motherboard USB port (don't use any USB hubs or PCI USB extention cards, this is important) and try to write firmware again. Try to write firmware several times. Try to write other firmwares. Try to write firmwares on another PC. Try to write firmware by using Octopus/Octoplus Suite Software (
Software).