If you are on a very old firmware you might need to rename the DH_DVRxx04HF-X-E(V2.0)_Eng_P_V3.200.0003.4.R.20170816.bin file to update.bin and then run the update in the DVRs UI.
Be sure to make a back up of your current config file. I've seen issues with the admin PW not working after updates like this.