camera lens doesn't close when it turns off

my samsung mv900f won't turn on. i thought it was faulty battery but i got a replacement and it's still not working. i may have dropped it but there's no dent or loose parts. when i take out the battery and press the power button, the light flashes green and the lens will close then open again then it just shuts off? and when i eject the battery the dot light thing flashes red a few times and then that's it. help????