I had exactly the same problem, it wouldn't charge it wouldn't turn on...
while waiting on the phone to HTC (yes I was about to send it back) I plugged in the computer USB charger-lead with the battery out! Just a few seconds later I put the battery back in and LET THERE BE LIFE...
So try... battery out...charger in/on...then battery in and see if that works it just did for me...I had tried every thing else before hand.
After searching for a week finally i found here ,
4 thumbs for you .