We've never heard of this model, from a quick search it appears to be a rebadged or region-specific version of a Hikvision NVR.
We are not aware of any custom firmware for this particular model, you would need to speak to who you bought it from and/or Hikvision support in your region.
Also, we did find this forum thread which links to some firmware versions for different NVR models that might possibly work for the DS-80239 model.
If you plug it into your local network you might be able to find it on the network using Hikvision SADP Tool and use the IP address to try logging into it.
If it is a very old model it might use the old default passwords (either 12345 or 123456) but it may have a custom password set, if you don't know this password then I think there is going to be very little you can do with this piece of kit and you might just be better off buying a brand new DVR.