Thanks Dan,
The failure occurred as soon as I performed the update. And yes, as you say, Hikvision insisted that it is the version for that serial number (Although the model name changed in my configuration).
Yes, it is really old. I am going to do what you tell me, and try now with another HDD.
I asked Hikvision support for a more updated firmware for an old DS-7208HFI-SVST. With the serial number and everything correct. They sent me the "correct" file and it turned out to be for the 7208HVI-SV. It stopped detecting the HDD, so, that version is obviously incorrect. They didn't take...