I applied the procedure to unlock a Samsung Galaxy S3 on a Samsung Galaxy Express I437. It went through smoothly, and but the phone was not unlocked. Instead, it gives me the error message "Phone not allowed MM#6" after I inserted a foreign SIM card. The procedure is reproduced below:
[1] UMTS [1] Debug Screen [8] Phone Control [6] Network Lock Options [3]Perso SHA256 OFF (after choosing this option, wait about 30 seconds, then go back one step by pressing the Menu button then select Back, now you are in [6] Network Lock then choose [4] NW Lock NV Data INITIALLIZ ..... wait for a minute then reboot your phone
Since this didn't work, I tried reverting NW LOCK back to the old setting. Unfortunately, it doesn't work. The unlock screen doesn't come up anymore. And I have no other way to enter an unlock code. Does anyone have any idea how to resolve this issue?
Million thanks!