Hello, i have NVR DS-7804N-E1/4P bricked when i flash wrong firmware DS-7604NI for it. So now it only boot to Logo then bip bip and auto restart. I tried flash TFTP very many time by set IP of my PC to 192.0.0.128 / subnet 255.255.255.0 and turn firewall is off. But no thing flashable although i can ping to 192.0.0.64. I have read a topic, it talk TFTP had locked in DS-7804N, it right? If can't by TFTP, can i use Raspberry Pi 3 or Usb FT232RL to serial it? I only have Raspberry and USB FT232RL Thanks you so much!!