iPhone 4 has no signal now
I have a jailbroken iPhone 4. I broke the screen and bought a replacement and installed it and the phone worked just fine except the screen was messed up. I bought another screen and just replaced it and the screen is perfect except now I can not get a cell signal. WIFI is fine and I get a cell signal sometimes just very weak and mostly when I am outside of a building. If I'm in my house or when I was just at work, I get no signal. When I walk outside It does pick up a signal sometimes. Did I mess up the antenna somehow or what is happening.