lm2, I'm gonna mark this as DONOTEAT and put it down to experience.

You do need to fumigate your device but I honestly don't know the real way to do it.
as for the moisture, you need to get it dried out asap.
If you are not brave enough to take it apart, get it into the airing cupboard or above your boiler or somewhere else.
you need to stop the rot, clean the contacts of the mmc board as much as possible - keep putting thick card in until its clean (we had to do this with the smart card slot on the cable box).

On the upside, at least you know the cause.



Warning sign icon because banana skins are dangerous.