My iPhone4 is not responsive to any button with no picture

I just replaced my digitizer on my JB phone. Once back together the phone is literally dead. I bought the entire phone assembly minus the battery and logic board and the phone still won't show any signs of life. I've tried switching the battery but nothing. I got another one and needed parts so I Frankensteined my new phone with my old one and now both phones are dead, even when I put the original parts back in I get the same result on both phones. I've tried everything. DFU, cleaning, parts replacement, cfw & factory restore , and recovery mode. Any ideas?