Hi jamie. You should try putting your phone in a bowl of uncooked rice and have it stay there for 4-5 days. More would be even better I think. Remove the battery and put it in a bowl filled with uncooked rice. The rice should absorb the moisture and hopefully will make your phone usable again. There is no guarantee that this will work but it's worth a try.

Reference: Wet BlackBerry Pearl Saved by Bowl of Rice

If uncooked rice does not help, you can always send your phone over to HTC to have them repair it.