I have something similar, a HEN08102. As for shorting the those pads, I tried it with gloves on. It made a spark and reset the DVR but it didn't reset the password, so probably best not to try that method! I don't have a serial to USB cable so I wonder if taking out the battery would work.. Anyone tried that? the trouble is.. it's fixed really well to the board and I worried I might break the bracket off holding the battery in..
recommend using usb, cost cheaper. solved the problem already using the instruction aboved. null modem+usb cable