LG G3 :: How To Get Phone To Connect To Cellular Network

My wife's phone stopped working last weekend. I went through the T-mobile technical care people and their solution was to replace the phone. Unfortunately the phone has a small crack in the bottom bezel so they won't replace it unless I pay the $175 deductible. I am hands on enough to fix some parts of the phone (I've replaced the screen on my G3 twice) so I thought I'd give it a shot here.

Her phone will work on wifi, but if you turn wifi off or if she goes out of wifi range her phone stops working. When the t-mobile person tried to have me manually connect it to the network, it said unable to connect to the network, please try again. We did a soft and hard reset. They tried to refresh my network connectivity and none of these options worked. We moved the sim card into my phone and it worked just fine. So obviously there is a hardware issue going on.