That's rotten luck. I fear the fact that it was powered up (vibrating indicates this since the battery is sealed) it may well be a deadun. The case
has to come apart, and I would vac it with something like a ShopVac if you can do that saspo - even with the case still on, get round the buttons etc., you never know.
I just might be the vibration depleted the battery and saved the day, but that is really clutching at straws. Powering it up on a USB was a bad idea - but you don't want to know that.
Anyway, try detailed drying, vac-ing more than blowing with a dryer, which only makes moisture go in further.
Worth a try.
https://www.google.com/search?q=htc+...w=1920&bih=902