For the camera with so impressive set of features you’d expect someone at Olympus would finally decide to implement a proper water-sealing system at the hatches. These gaskets are simply too sensitive and unreliable. As always, it leaves an impression of purposefully created weak spot, which will never be covered by warranty.
Also, Olympus (and others) could significantly reduce the possibility of water ingress by creating one single access hatch sealed by o-ring, instead of two, sealed with their funny gummy-things.
Third, it is never wise to charge the battery within the sealed casing. Aside of augmenting the explosion force, it heats up the case interior. This may later cause port / monitor fogging.
As to the fogging you mention, the humidity possibly remained from the camera assembly line – no need for additional water leak to create it.
One of the best ways to remove fogging would be to replace the inner air volume with nitrogen. It is not difficult, as any tyre service has it…
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.