Why can I not connect to mobile network after screen swap + Lost IMEI?

[AC Question]

why can i not connect to mobile network after screen swap + Lost IMEI

i have an s3 LTE and screen and lcd was broken so took motherboard out and transferred to a handset with a healthy screen. All connected back up fine but initially lost the IMEI number (came back after a while but has disappeared again since factory restore) and also been unable to connect to the Virgin Media network. WiFi runs fine.
What can I do to get the mobile working 100% again?

 

[B. Diddy]

Re: why can i not connect to mobile network after screen swap + Lost IMEI

Welcome to Android Central! Is the SIM reader part of the motherboard, or is it separate? If it's separate, perhaps there's a problem with the connection.

 

[caroky]

Re: why can i not connect to mobile network after screen swap + Lost IMEI

Hi B Diddy. The sim reader is fixed within the motherboard although I see replacements sold on Amazon etc. The single screw which fixes the mono down did seem to bend downwards so if there is an onboard connector it may have become loose. I will check. Any ideas re the IMEI going awol?

 

[B. Diddy]

Re: why can i not connect to mobile network after screen swap + Lost IMEI

Sorry, I don't know why the IMEI would have disappeared.

 

[caroky]

I worked it out from reading other forums and realised that the i9305 is slightly different in terms of the plastic housing to the i9300. So when I fitted the i9305 mobo into the i9300 frame, some of the contacts were out and part of the frame was pushing onto the chips. Anyway, I bought a genuine i9305 screen and swapped the mobo and other components and all sorted. My only remaining problem is that the network signal bar randomly drops to no signal and is generally weaker than it was before.