In step five, under the cover there are two round connectors, in my mini s5, when removing the cover of the connector is the left-desoldou (only on your right side) and is now only soldier left side.
After loading a new screen and assemble everything, I found that the phone has poor GSM network signal and sometimes is without sign.
The fact that this pin can be desoldered having the cause? Or this connector has no relationship with the GSM signal.