I think ive said this before, but do you know how many dead ends you reach on the forum due to people discussing or asking for a file, yet none being actually mentioned or linked too. Anyway did a bit of google searching and found
auto - update tool - Tools - Download - Support - Hikvision for the auto-update
tftp tool and instructions. Using the tool I found at that link, i successfully updated to 5.2.5. Very strange it wouldn't do it from the web console though. any ideas would be welcomed as i wouldnt want it causing issues going forwards.