need help please g928f

hi all got a g928f the other day been repaired before via z3x problem is its running 6.0.1 XXS3BPIA with lastest security I made the mistake of downgrading modem to repair imei but when I reflashed the phone and updated it to 6.0.1 again xxu3 its null/null updated modem still null/null/ and when a add it to z3x box it wont find modem or when I enter #*06# or #*0011# nothing works please anyone that can help