iPhone SE - no signal after a fall

Hi! I got the iPhone SE. A few weeks ago the iphone fall of the stairs and the LCD just broke. I changed it but there is a new problem: I haven't signal. Is looking for signal all the time and later appears "no service" and a few seconds later is looking again...

Some cell services tell me that probably is the motherboard and others tell me that can be the module of the lighning connector.

Someone here has the same problem or any idea? Thank you so much!