Logic board iPhone 4 switch

I would first like to say that I own two Verizon iPhone 4 s, they are both MINE. My iCloud account is registered to my email on both and I have backups from both on my computer. I've read other questions and heard answers telling them that they must have a stolen device or something and I'm just stating for the record that neither of these devices are stolen.

The first phone I've had for years, registered my phone number under my ex's account, we split, he locked the phone. Same old story. So I buy a new iPhone 4 (they are both the same type of iPhone 4) but about six months ago I dropped my newer phone down the stairs and the screen broke, it still works then about three weeks ago it will no longer take a charge. I put the logic board that doesn't have a locked MEID number in it and put it inside other iPhone 4 that doesn't have the broken screen. It powers up and seems to run fine except the fact that I still can't get phone service. Is the MEID not on the logic board? How come it won't work? Do I have to switch the logic board back and take the good screen, back and charging port off and put it on the other phone? Rather than switching just the logic board?

I know that I could just go buy a new phone but they're expensive and if I can avoid dropping that kind of money I will, especially when I should have enough parts between these two phones to get a working one. Right? or am I crazy and now that I've taken out the logic board am I just out of luck?