Note: I am, in anyway, not responsible for whatever may happen to your phone, but i am sure is work for unlock 100% de samsung GT-S6500D because i tried for my phone Samsung mini 2 GT-S6500D
I'll tell my story to unlock my samsung, I tried to unlock several situations.
the files nv_data.bin I had it in my efs folder and not the other files and not BLM5 STL5 dev folder.
Then I try to explore all the files without success.
And finally I had the idea with the secret code to unlock my samsung and then I do now that I do I share with you.
1-My phone is Roote possible you can try whit the phone not root and without sim card and you can also back up you file maybe.
2-check if your phone Go to dialer and type: *#7465625# look if you blocking network is ''on'' your phone is lock then clic ok
3-After Go to dialer and type:*#197328640# you have this is menu and touch de screen  DEBUG SCREEN
4-After you have this is de menu and touch de screen  PHONE CONTROL
5-After you have this is de menu and touch de screen  NETWORK LOCK
6-After you have this is de menu and touch de screen NW LOCK NV DATA INITIALIZE
look Foto-4 wait 1 of 2 min your screen freez
and after turn off your phone and restart your phone is unlock enjoy can now dialer and type*#7465625# and look de screen all off
and after you can Dialing *2767*3855# clear all locks!
Info:For those who have bad affects the right number it is possible to go back menu button just the left button
I wish you all those who have a phone samsung gt-s6500d and gt-s6500 and its possible that works for other samsung but I can not confirm that and forgive me for my english not very good .