I'm a security tech but my company's primary dvr is a pc based system. We have a couple of dedicated micros dvr's in the field and I like them a lot so when I noticed you can buy them dirt cheap on ebay because of their supposed difficulty of replacing bad hard drives I bought a few over the years, each time replacing hard drives and reloading firmware with no issues. I was using 10 cameras on a 16 camera unit but was a little disappointed with the refresh rate so I got the bright idea to replace it with a ds2p six channel and a d4. The ds2p went great, bought it for next to nothing with a bad hard drive, put in the drives from my old unit and updated the firmware and was good to go, it blazes along at 120pps with no issues whatsoever. The d4 was supposedly a working unit when I bought it, but when it arrived it would'nt even go into bootloader. When you plug it in it beeps 21 times with no video out whatsoever. The seller claims he's 100 percent sure it was working when he packed it up. I'm thinking the hard drive may have taken an impact in shipping, but all my other dedicated micros dvr's would go into bootloader regardless of a bad drive, are the d4 models different in that regard?
Nevermind, it turned out the drive was bad but it wasn't the problem with the blank monitor, I prepped a new drive and popped it in. The dvr then booted up and started recording after a few minutes, all with no monitor out. Upon further inspection there was a scorched area of the PCB in the region of the monitor output and camera one input. I'm gonna return this thing to the seller.