Why does my S2 i777 keep saying mobile network not available and how do I fix it?

[AC Question]

My s2 i777 keeps saying mobile network not available

I've factory reset it so many times. I checked the sim in another phone & it worked. I just replaced the charging port & since I've done that it started messing up. The speaker doesn't work now, it isn't recognized on the computer. I have no warranty. Idk what to do. Could it be the antenna? What's the antenna exactly for?

 

[B. Diddy]

Re: My s2 i777 keeps saying mobile network not available

Welcome to Android Central! You probably disrupted some connection when replacing the port. Open it back up again and check all of the connections.