I accidentally cracked the digitizer on my 9930 a few weeks ago and ordered a new one in the mail. I received it today and after I replaced the old one, my lcd screen stopped working. I tried to plug it in to my computer and it wouldn't connect to the blackberry desktop software because the phone was rebooting. Whenever I turn it on, it gets stuck in some rebooting cycle. Any idea of what I might have botched when trying to fix it? What can I do to fix this?

Nobody can tell you what you did/failed to do. Did you order the correct digitizer? On some models (like the 9700) there were several different model digitizers and the only way to know which one you had was to look at the part number on the back of the old one.

You can try disassembling and reassembling the device again. Otherwise there is no way for somebody to know what you did.