My replacement digitizer will not connect to the phone.

I have an iphone3Gs

Part 2, my digitizer, will not connect to the actual phone itself. We've put the entire phone back together with no problems, but I can't get part 2, to lock into place. I've looked at it very carefully and it looks like it should fit, but it won't stay down...

I tried putting down part 1, hoping that would secure it into place.

At one point, I was able to turn on my phone and it lit up. Full battery power and everything, I just couldn't use the phone because the digitizer wasn't connected....

While trying to fix the digitizer, parts 1 and 3 came undone. I've put them back; but now the

phone won't even turn on.....