I have a Hikvision DS-7608NI-E2 with 7 Hikvision DS-2CD2142FWD-I cameras, all purchased new and installed together 2 years ago. The system has worked flawlessly until last week, when I noticed that no cameras are displayed in live view. I'm seeing no POE lights blinking, except on startup of the NVR. I assumed the POE block was dead and ordered an identical replacement Hikvison NVR, but today after install see the same problem as before. The setup has never been connected to any network, and no changes have been made by me since the original installation. Can someone help me troubleshoot please?