Cha Cha locked

Hi my Cha Cha has shut down, I thought it needed charging but when I charge it the charge light flashes red and then green... Its been on charge 2 hours, when I try to switch it on it goes to the HTC screen then closes down. I have taken the battery, sim and memory card out and then put them all back in. I do not know how to get my phone back on? Please can someone advise me what to do?

Thanks
Sheri