I have a DS-7208HQI-K2 that had a failed update. The monitor received a signal but stays black and nothing else shows up. Nothing on the SADP tool. Will this work to connect to the serial port. LC234X. I'm new to this and have some reading to do.
If that's a DB9 connector on the back panel (as opposed to a 4-pin connector on the main board) it will likely need an RS232 interface and null model cable as opposed to the USB to TTL serial interface of the device in the link.
Actually - looking at the device data sheet, the back panel has an RS485 interface.
I don't know if that supports the serial console.
My suggestion would be to check the main board for an unconnected 4-pin 1.5mm ZH JST connector.
If that exists - it will be serial TTL levels and should be OK for the device you linked to.
But you will need to buy some wired connectors to hook up to it.
It looks like there are 2 candidates, JP10 and JP12. I'd try JP12 first.
To test, if you don't have a multimeter, connect the GND of the convertor to the chassis, and try the RX of the convertor on either of the 2 centre pins.
With the terminal program (PuTTY works well) set to 115,200 baud, 8 bits no parity, check for output when the DVR is powered on.
When you get that, connect the TX to the other centre pin.
One of the outer pins will be 5v, one will be GND. But I don't know which as I'm away just now. You could just leave GND connected to the chassis if that works.