Backlight + Mic Issue

So I have an iPhone that has come in for repair. The Microphone didn't work. Replaced the bottom Microphone that is attached to the Dock Charger. Didn't fix that Microphone issue. So I had another iPhone 4 laying around and decided to try that Logicboard inplace of the Logicboard of the non-working microphone.

Replacement Microphone/Dock + old Microphone/Dock worked fine. Can only assume it has to be a logicboard issue, did a quick look up and turns out its the audio compiler ic. That's fine, whatever. I reassembled the first iPhone 4 that originally had no working microphone. Got it reassembled and now the backlight is gone.

Any ideas? I've tried a soft reset, i've tried reseating and cleaning the connectors. I'm not sure what else could be the issue other than Backlight Fuse + Coil which, pardon my language, would be an entire !@#$% to fix.

I'm just looking for any extra potential fixes i may have missed that doesn't require soldering.

Update: We have tried other screens to ensure it wasn't a screen problem.