Any clues? HDD failure or power supply?

You didn't give a model number but I believe all their NVRs have a separate light for power, HD, and network. If the power LED is flashing, then you need to check the power supply with your DMM and make sure it's within spec.

Again model number! Does this NVR have a built-in power supply or an external brick? Even with it built-in, many of those have a separate power supply board inside that is easily replaced. I have a power supply board for a 16ch POE enabled unit in-stock.

I tried to get the model number, but it was somebody else’s lousy install, without even enough slack in the cabling to slide it out and disconnect or look at the back side in any way.

Generic from the client.

NVR 8CH 8POE H264 HDMI 8TB HD H.265

That probably is an internal power supply (1U style). And the one I have won't match it.

It use to take about a week to get a power supply from Hikvision. With logistics & the chip shortages these days, who knows.
I believe it is made by Delta Electronics but I haven't found a supplier state side that sells those models.

I'm sure you know what cost is on those 8ch NVRs from Hik. Considering how cheap they are, it makes more sense just to buy a new one rather than screw around with trying to repair it.
[Link: amazon.com]

Is there much setup to replace the NVR?

I don’t do these normally.

Not really.
If all the cameras were Hik as well, then the NVR will auto detect and populate the cams into the new NVR, that are plugged into the built-in POE switch.

You will need the login for the cams - if they aren't sure they have that, price will go up XXX. Because you will probably have to go to each camera and do a factory reset.

Then it will just be a matter of configuring the network settings and router they are using.
Remember to always change the admin account to a different password AND "name"! And change the ports used from the defaults!

Bonus points if you then create additional user accounts for the owner and anyone else they want to give 'limited' access to. This only applies if you are going to be the one managing the system from now on, otherwise let them screw with it however they want.

That is good info, Brad, thank you! Now you say the cameras will auto populate, which makes me think they will be visible, yet you say they have to be logged in?

In the interface, any Hik IP cam (and many ONVIF IP cams too) will auto detect and get added to a list (refreshed every few seconds). Then you choose all the cams you want to import.
In the case of new Hik cams, you enter the new passwords you want to setup for them in the 1st step. In the case of cams already setup or other manufacture cams, you manually enter the existing credentials and then choose your new passwords.
The only time this gets frustrating, is when you have a cam that won't auto populate. Very rare but it does happen.

[edit]: Think of it like this. The NVR is constantly running a FING search on its POE ports. When it finds a new device it recognizes as an IP cam, it gets added to the list with whatever info it knows about it (again, think FING). You can then choose to, or not to, import that device to the NVR setup.

Client called and new NVR not recording.  Isn’t that the default?  How could it even get shut off?

Well, it depends. Is it a Hikvision or some other generic brand?
I would think whoever did the initial setup didn't get something right.

There are so many variations we could be looking at here, it is impossible to really give any good advice. Would need to know the exact model number, what firmware it is on (that is becoming important these days, as different firmware versions can act very different too). What brand of IP cams. How these cameras are getting to the NVR (direct feed to the POE ports on the NVR or thru the common network using ONVIF).

Looking back at my replies from 6 months ago, maybe saying it was simple was incorrect. It's simple if the installation was done correctly, using modern equipment, paired with fully compatible cams.
Since we don't know if this guy is even using brand name equipment with North American firmware, let alone if anything has been installed correctly, I would pass on this job. Especially since it seems he's dragging this out 6+ months now?
Unless the customer is willing to pay for a complete install with possible new equipment. If it were me; for an 8 camera system, that would start at about $4K and go up from there depending if I had to re-run wiring as well. Anything short of that, I would walk from what I have understood.

You better believe any 'professional' CCTV company would do the same thing. Gut, replace, re-install. Which is why the guy is trying desperately to find a Ring Leader for his Circus, he doesn't want to pay.

I should have given more info.

This is LTN8608-P8 with 8TB hard drive.

Hikvision branded and sold by LTS which is a major US supplier with good tech support. I have an email in with them now.

i think they are LTS cams also.

LTS remoted in and did setup back then.

I should have passed, I was trying to help a contractor friend. Now I am deficient in understanding and troubleshooting skills on this system.

I'm familiar with LTS, I have an account with them.
Although I don't use it much because = years ago I lost 2 separate bids when the customers contacted LTS directly. LTS aggressively priced against me (giving customer 5% off dealer cost). Same $hit Lutron does to small dealers once in awhile. Makes no sense what-so-ever since ultimately they are competing against themselves and getting 5% less money. But whatever, left a bad taste in my mouth.
Also note: although LTS cameras have been great. I have found the LTS firmware on their DVRs & NVRs to be very buggy. Make changes in the software and it refuses to take. Some things might revert after a power failure. Or features just not working the way they are suppose to. Add to the fact they discontinued the residential video Doorbell (Hik is still making a great one they can OEM), and I avoid LTS like the ....

As to your current problem = Like I mentioned, LTS has buggy firmware. The thing that should be done NOW! Go install the latest firmware (NVR5_V4.61_230110) for that NVR. It literally just released 14 days ago. This may fix some buggy issues. Note: If the current firmware is older than V3.4.96, your screwed (can't upgrade the regular way) and very likely what's causing issues.
Also note: after doing the firmware upgrade, go thru ALL the settings to make sure everything is how you want it - 8ch system should take less than 30 minutes to get thru the whole menu, even being as meticulous as me. You can also save a copy of the config file.

Thank you, Brad.

Revisiting

Is a static IP necessary for this NVR?

Starts with 172.xx.xx.xx (I know it's public, that's what's here)

Its AT&T 12mB/s

He's thinking of switching to Comcast