[condensr]

Take Nancy's advice and remove the batteries, and leave it sitting in a warm dry place, without the battery cover on, for several days AT LEAST. Don't get in a hurry and try and use it any sooner- if there is a possibility that it is OK, rushing things could very likely kill that chance.

If it doesn't work after that, you can try calling Dexcom and pleading your case, but I wouldn't hold my breath on the chances they'd replace it for free under such circumstances. Though, you never know, so it doesn't hurt to try!