My Samsung S3 got locked after installing ROM, Newbie Help

[nauman1]

Hello,
My first time posting here.
I got a used smasung s3 phone from someone.
After that i installed a new ROM , that was my first time Installing any ROM.
after installing, my S3 got network locked and asking for network code on start up. I searched forums, got different suggestion but nothing worked out, and i had to get it unlocked from some mobile repair shop.
Now i want to install some other ROM on my S3, i have concerns for same issue again.
My quries are,
1 : Will my S3 get locked after every new ROM install?
2 ; network lock code is based on ROM? i mean if i install a worldwide open ROM, it will not get locked? or network code is something different that ROM issues?
3 ; Can i take backup of my mobile in the case if after installing new ROM it gets locked, so that i can go back to revious status? Is it possible?
4 ; Is there any thing / folder to back up , so that after installing new ROM i can get my mobile unlocked?
5; i am reading about EFS thing, does it mean if i backup that folder, i can get my mobile unlocked for new installation


I knw these are v basic Questions, but i am searhing in forums to understand these things, can someoone please clear me or can point me to some thread where these issues are answered.

Thanx alot for help.

 

[Hopeless One]

First of all, welcome to the forums. So the issue might be the ROM, not the phone. I've flashed around 6 different ROMs on my phone and never had such issues. So it might be ROMs failure. Try installing another one and pay attention to the details, if you flash ROM for different type of S3 you might even brick it.
About backing up, I'm using Goo manager and it allows you to back up whatever you run now and then in case of an emergency to roll back. It's called open recovery script. Or you can search for some other application. I'm pretty sure there are a lot of them. If you want to backup specifically o e or more folders, I'd suggest you to use Titanium backup (requires root rights).

Also the beauty of goo manager is that it's foolproof. It won't allow you to install wrong or corrupted ROM on your phone.

Posted via Android Central App from rooted SGS3 running CM 10.1

 

[nauman1]

Thanx alot for quick help .
Can you guide me which ROM i should install?
Does it depend on installing any country based ROM and some international ROM?
and does it matter on samsung based ROMs and CM based ROM?

Thanx

 

[Hopeless One]

Well the ROM will depend on your model number. To check that, go into settings -> about device and check the model number. For international sgs3 it's GT-I9300 for US versions like AT&T or Verizon it will be different.

Try installing Goomanager and first of all do the open recovery script (it will remind you to so before flashing just in case) and search for ROMs. It should show you only available ROMs for your device, it will ask you your device version on startup so make sure you check it first and confirm it. After that find yourself suitable ROM, download it and make sure you download Gapps too, otherwise you'll be missing play store. Then after it completes download it will check again if it's not corrupted or not suitable for your device. Then you can flash the ROM. Make sure you tap on flash selected ones and select ROM first, gapps second. It's important.

About the region stuff.. I'm not quite sure about it, but I guess it doesn't really matter, but don't quote me on that one.

Good luck and have a nice day.

Posted via Android Central App from rooted SGS3 running CM 10.1