Acer Mobile Phone Power Issue

I have an Acer-beTouch E400 mobile phone.
At first I am very delighted with this phone but after I recharged the battery, it started to freeze and hang.
The power signal has a (?) symbol. I took out the battery for a minute and then put it back again and switch the power on.
The Acer company logo appears with (!) and my mobile phone did not start out and it stopped working.
How can I fix it?
Do I just need a new battery or my phone needs a replacement?
Please help.
