sounds to me like the board has got wet, id say take the board out of the gun and make sure there is not water or mud behind it, leave it out somewhere it can dry out for 24 hours just to make sure there is no moisture hiding anywhere then try it again.
when you take it out of the gun have a good look at the board for signs of corrosion, they are covered with a water proofing but you never know.
if you are still getting nowhere then id say you may be right the board could well be done for, in which case have a word with Stoney on Tuesday once he is back from Germany about a replacement or sending it in for someone to have a look at it. alternatively hang on till the next cpps and ask our tech there to take a look BUT it would be worth speaking to Stoney first to make sure the tech has a spare board with him.