Bent phone - no signal

My iPhone 6 is fairly bent. Following the bend, my phone was fully operational (screen undamaged) for about 4 months. Over the past week and a half, I've lost cellular signal. (Wifi still works) I've tried to reboot, reset network settings, and reset SIM card. All of these fixes worked for about an hour until the phone goes back to "Searching.." I took my phone to the Apple Store but they were of no help, only suggesting to replace the phone. If I open up the casing and take a look inside, what should i be on the lookout for? Antenna? Motherboard damage? Any help would be great.