Can't unlock my phone

[Richard Desgnr]

I had a unlocked Samsung Galaxy s3mini that i sent to samsung for repair & they replaced the motherboard & it came back LOCKED.
AT &T gave me the unlock code but i already tried different codes & it Is permantely locked.
I did a Hard Reset & now it won't let me unlock it.
How can i reset it to allow the unlock code.

 

[Almeuit]

Well technically you can't force it to take any password .. except the one that was set. I would call Samsung and ask why it came back locked.

 

[Richard Desgnr]

It came back locked because they changed the Motherboard!