changing the chasis cause "searching" no Baseband BUT yes IMEI

All the stuff I found in internet about no Baseband firmware is joined with no IMEI number

I have checked some cables inside but still thinking that maybe the flex interconnection between upper and lower side of logic board could be the cause

I've changed the dock and 3G antenna but without solution

I think that restore will cause a brick but OTA is not able to achieve because of the error during checking system in the iPhone

Could be solved UPDATING from iTunes? Afraid of not to be able to activate

Important to note that IMEI is still present but not network, searching with and without SIM inside