MurphyWasRight,
Not sure I see the point in trying to detect water/moisture inside the module when it is very low risk to open it and have a look.
Things other than water such as a cracked PCB that can also cause problems.
MurphyWasRight, as you know "Murphy´s law" never fail. My idea is:
1) More you know about the internal condition of the "pressure vessel"
safer and faster will be the job of the investigators. And this IMHO is very important. Not just for the lengthy bureaucratic processes but to ASAP understand what happened (the global picture)
2) The PCB´s inside the well designed CSMU certainly are not prone to crack.
There is a picture i guess i posted earlier with the internal view of a "non cylindrical shape" of a similar CSMU for the SSFDR 4700, the one of F-GZCP.
Probably the cylindrical shaped is even better than the one showed in mfr. website.