If you have a Night Owl Security System DVR and it won’t boot there are two known problems.
The first is a bad hard drive. When the drive goes bad it may make a clicking or grinding sound or may not make a sound at all and the hdd light on the front of the unit will probably blink and you may get a beeping sound and the system may not boot. If the system does boot go into the Night Owl DVR’s settings and try reformatting the drive as sometimes a bad sector or corrupted file or partition can cause a problem and sometimes that helps. If that doesn’t work attaching the drive to a computer and running a drive repair tool which can mark bad sectors may fix the problem. But most likely the hard drive will need to be replaced. Luckily it’s not that hard to do since the software of the system is hard-coded into the motherboard. Just unplug the unit from the power supply and unplug all the cameras and other cords so that you don’t get shocked and unscrew and open the case to the DVR and unscrew the hard drive from the chassis and detach the power and SATA cords from the drive, insert a new drive and reassemble and reboot and once inside the system format the drive using the hard drive settings just as you would normally. You don’t need a very big hard drive to replace the original and in fact you’ll probably end up with an upgrade as a one terabyte 3.5 inch hard drive from some place like newegg or tigerdirect made specifically for security systems runs about sixty dollars after tax and shipping and that will work just fine.
Now if you are having another problem where the system simply won’t boot, but you can see the night owl logo and it never goes away, the problem could be that you configured the system to connect to a network, but that it is currently not connected to a network or network router. For some reason this causes the system to hang on booting. (Probably it is trying to acquire an IP address or set the date or something.) To fix this just plug it into a network and you should be able to get the system to boot and then you can reconfigure the network settings or configure it to not connect to a network at all which should prevent that problem in the future.