Problem with 7280, please help

[chaniilove]

I am new to blackberrys, so forgive any ignorance on my part. I have a 7280, it is temporary as I waiting for a 7290 to arrive, i was sent the wrong model. But in the meantime, it arrived wiped clean and we had to reinstall the os (it was getting error 507 and would go any further). Now it boots up, I enter my password, and I get the home screen with the messages, calendar, alarm, calculator, etc icons. From the instructions I read you are supposed to hit the phone button on the top of the phone or the space button to enter phone mode. However neither of these buttons go to phone mode. The space button works fine when typing a message, and when i press either on the home screen the phone beeps and the buttons click normally, but nothing happens, it stays on the home screen. I have my sim card in it and it has full signal, wireless is on, gsm has 5 bars, and its fully charged. if I call my phone number from another line the blackberry does not ring, a little arrow icon comes up in the upper right corner until i get voice mail on the other phone, then the arrow goes away. It beeps when that happens. And there is nothing else changing on the screen when its ringing besides the arrow coming up and going away. Hitting the phone or space button still does nothing to answer the call. I think thats all the information I can provide. Does anyone have a clie what the problem might be? I'd really like to have a phone again...i wont have the 7290 for another week or so at least...and this is very frustrating
Thanks for any advice or ideas
Rachel