Last night my Centro was dying so I put it on the charger. I have to hold the charger a certain way or put it in a cup to get it to charge, but at least it was charging. It was a little more than half way charged when I unplugged it to use my phone. After the call I put it back on the charger, that was about 12am. I woke up at 4am and checked my phone. The red charging light at the top is on and the lightning bolt over the battery is on but even after 4 hours it says 0% charged!
I took the battery out and put it back in, it says it needs a password, but I don't know the password!
Took the battery out again, now the phone won't even turn on! The red light is still on though!

Is it the phone or the battery that's causing problems? If and when it decides to turn back on how do I reset the password?

I got the phone used in May.
It hasn't been HotSynced