Is worth trying what Mr Paul advised above with the link to taking the fuse board apart, more so if you are having problems getting a replacement .as you have nothing to loose in having a look to see if it can be repaired,, had water problem in mine once and sorted it by taking apart and cleaning the small part of the board that had shorted out with some fine emery paper, lesson learnt never leave the fuse/battery cover off.
Just make sure you take a pic of the board before removing fuses/relays to help re-fitting and place them in an order on table that makes it easy to remember to re-fit them,,plus as you have had water in the board best to check all fuses as you may have blown one if you had water in the area.