network slot 1 issue

[gopla]

Please help me...sim slot one not working sir when i tried the code *#*#4636#*#* before typing that code it was working well.i have htc desire 816.after the problem i rectified my manual setting with the help of another htc 816 and my problem got solved but after few days after restaring the phone network have been not coming.please help me sir.i went htc center they told we need to change mother board,but how come is this when problem happened while typed *#*#4636#*#* as soon as i tried to change phone information setting correctly network went off...