S2 Issues

Hi Guys, I've read the threads and I couldn't find any relevant to my problem. I took my phone out of my pocket today and it had switched off (no biggy) turned it back on and it loads the Samsung screen showing the phone number and my carrier's sign but then it just shows the word SAMSUNG flashing over and over. It won't go past this screen, i've taken out the battery and sim and put them back in again i've plugged it in and it charges fine but it still won't get past that screen. I have even tried a hard reset of the software and i left it for 5 hours and it still was stuck on the screen saying it was "Downloading the software" PLEASE HELP!!!