My girlfriend had this same issue last night at 4 in the morning. It's finals week so that makes sense.
I had her leave the phone with me after we "charged" it until 7am.
I tried holding the power for 30 seconds plus. Didnt work.
I tried holding the power + up button for 30 seconds. Nothing.
I plugged it into this laptop, and it detected and installed drivers. I tried doing those steps again and got nothing
I GOT IT WORKING by holding the power, the laptop would "bong" like it was being connected/disconnected and repeatedly pulling the USB from the laptop. I held the power with my left hand and USB with my right. I plugged and unplugged the USB about 7 times in about 5 seconds just while holding the power button down.
The tiny red dot showed up. So I let it charge for about 40 minutes and hit the power. The light turned off!!
After I held the power button I got the HTC intro screen. Seems to be charging.
Does anyone know if this is a hardware or software issue. She's not a fan of the phone lately and if it's going to keep doing this, it's time to find something more reliable.
Thank you guys for this thread. I made an account just to reply to it and say what worked for us.