Signal issue after lcd replacemet

[rzinformatic]

Hello to everyone.

I bought a lcd screen + frame  to replace mi z3 with lcd broken.

After change it , I have serious signal problems , outside it works fine ( gsm and 4g ) but in my house or another closer places my z3 has low signal (1 bar ) and  continiously it losts signal.

I open it and check the parts , all looks good, so I have identified 5 parts to may be working wrong :

-Antenna cable coaxial.

-Bottom plastic antenna ( black with some gray lines)

-Bottom board ( where antenna cable connects )

-Top connector socket (in motherboard) 

-Top plastic antenna ( It says 'sub1')

So my question is , all this parts works to have signal?  there is a way to recognize what part is not working ? 

I want to buy the replace parts on ebay , so I want to know what I have to buy.

Thanks in advance.

[Uliwooly]

@rzinformatic

Pretty much trial and error unless you get it inspected by your Local support, you could buy a new antenna and check again.