Just replaced screen but phone has stopped working properly

Ok so I used the guide for display assembly replacement and finally 100000 little annoying screws later, it's set. However, now the screen is totally black and is completely unresponsive. If I plug it into my computer or car it makes a beeping noise, but that's the most it'll do. I asked someone to call me and instead of a ringtone I got a strange repeating tone that sounded like something crashing. I undid the battery (power cycling i think it was called?) and made sure the three ribbons are in there tight. I've also held home and lock buttons for significant portion of time. If I plug it into my computer it does show up in iTunes. There are no sounds otherwise. I have no idea what is up, only that it is not working. I got to school far from any apple store and I have to have a working phone before spring break friday. Pleeeease help