Someone PLEASE help! I'm having problems with my digital camera! =[?

Hey everyone. Well I have an Olympus digital camera. Last weekend I spent the night at my friends house and I brought the camera along with the charger. My camera died so I took the battery out to charge it. I know that sounds weird but I have to take the battery out and put it in this square thing that you plug into an outlet to charge it. Anyway, it was charging for a half an hour, maybe 45 minutes, and then I put the battery back in my camera. I know that I didn't charge it long enough but it would last for a little. Anyway, when I tried to turn on my camera it wouldn't turn on! I didn't drop my camera at all, and I didn't put the battery in the wrong way either because the cover for the battery won't close unless you put it in correctly. Does anyone know what could be wring? Should I get a knew battery? Also, one of my friends was saying something about a "hold" switch, but my camera doesn't have one of those. So that's not it. Help PLEASE! Thanks!