my htc dhd wont work

hi im new to this forum. iv had my htc dhd since xmas never had any problems with it but after leaving it to charge overnight when i went back to my phone it was turned off and wouldnt turn back on.
tryed charging it and it wouldnt charge.
so i thought it was the charger port that was knackerd. so i swapped battries with a friend.
and it still wont work it makes the start up sound and the bottom sybols will light up (home and menu ) and it will take a charge now but nothing is coming up on the screen.
any help would be welcome

Hello according to me there will be a problem with your phone. If your phone is in warranty then take it into the service center of HTC and tell them about your issue. Remove your battery for five minute and again put it and do not try to power on it just charge it fully and if it’s still not working then go to the service center.

thank you for your reply. but now thew battery wont take a charege it must have gone dead last night. i havent got a warrenty i bought it from a friend. but i will try what u suggested. my friend has dhd on contarct could he say mines is his and send it in. or would the serail numbers be a give away??