So if you have had water ingress on to the top of the CEM it can cause the connectors that are on the top to corrode so even if its not wet when the fault occurs just going down an uneven road or over a bump can cause movement and then you loose a connection.
You really need to look at the top of the CEM to be sure as I suggested.
Have a watch of this
https://www.youtube.com/watch?v=U8UozG9qLvM
Its USA based so the CEM is on the opposite side to yours but it will give you an over view and you can see the connectors on the top of the CEM that suffer when you have water ingress.