Did you ever get this resolved?
I've bought the same NVR, the 4CH version, and have the exact same issue. I've upgraded to the latest firmware but cannot get it to unbind...
Any help would be much appreciated
DS-7604NI-K1 / 4P(B)
serial: 0420180913CCRRC51176227WCVU
Firmware: V4.30.097 build 240401