This...exactly. The filter and o-ring are missing and the torque for the din connector on a DS4 is 20 nm. As long as nothing is damaged, buy a DS4 service kit to get the filter and o-ring and reassemble and you should be good to go. If you found the filter you are in even better shape since that o-ring is the same as a blanking plug o-ring so is easier to source. If the threads are damaged then you may need a new DIN connector and/or a new body depending on the extent of the damage. Luckily not a big problem and certainly easy to fix. In the below diagram you are missing 25 and 26 (unless you found them when it happened).The o-ring and filter are missing in the pictures
View attachment 571545
It takes several turns until the o-ring seals both the housing and the connector. If the connector is loose, it will leak.
If the housing was blown off the connector, it must have turned loose nearly all the way. That would have been visible, since the black spacer doesn't line up anymore. So the problem occured during disassembly at the previous dive.
Tightening the connector with a torque of 20Nm is required to keep it in place.