iPhone 5s isn't turning on after battery replacement

I replaced my iPhone 5s battery but unfortunately I didn't keep track on step 11, Remove the following screws securing the front panel assembly cable bracket to the logic board, along with loosing one of the screws in that step also. I followed the rest of the directions, but now my

Phone won't turn on. Is it because I lost one of the screws, and can I order labeled screws, I can't find them online. Or did I receive a faulty battery?