Hikvision DS-7216HVI-SV not detecting by Hikvision TFTP tool

[alizain 0]

I tried to downgrade DS-7216HVI-SV using TFTP tool by hikvision but something goes wrong and now when i start dvr it never boot only black screen, i tried to use TFTP tool to again but now TFTP not detecting the dvr. several times i change ip to 192.0.0.128 and also tried with ip 192.0.0.64 but no success, please any having experience about this issue guide me to recover dvr firmware.