Actually, my dealer is not an authorized one, according to the Hikvision website. Somehow, they still had access to the new unlock tool and were able to generate the unlock code for me. They still haven't responded to my question about upgrading to the latest firmware. I don't want to do the FW upgrade without the dealer's "blessing", and find out that the Admin password is changed again, forcing me to repeat the unlock procedure.
At this stage, I'm going to keep the Hikvision cameras and return the NVR. I'll build a Synology SS instead, since I've had good experiences with their enclosures.