Originally Posted by EGSuda
I'll get this out of the way first, I'm pretty new to rooting and flashing ROMs. The only thing I've ever rooted before was a free Kindle Fire I got from Amazon, and got some version of Android on it a looong time ago. Now I want to get LiquidSmooth on my Galaxy S3 i747. I'm completely willing to follow all noob guides by myself namely http://forum.xda-developers.com/showthread.php?t=1802160]this one
HOWEVER, since this is a phone from AT&T with a data plan, texting, and calling, and not some free Kindle with none of that, I'm extremely paranoid to do anything risking losing all these features. There's really no clear indication anywhere that this will or won't happen, since I assume this is either just extremely common knowledge, and most trouble shooting is about screwing up in general or bricking.
I have the same phone and there are a few things that are good to know that will help you and possibly keep you from making a bad choice.
Have you accepted the 4.3 OTA update from AT&T on the unit or...? If you have, then you have upgraded to a specific bootloader/modem and can no longer downgrade those items without causing problems.
Originally Posted by audit13
If you took the 4.3 OTA AT&T ROM update, your phone has the 4.3 mjb bootloader.
To confirm which bootloader is on your phone, boot into download mode and let us know what it says on your screen.
If you did not take the update then you dont have these new items and your options are more open i guess.
First, your going to need to root your phone, without tripping the flash counter. There are lots of guides on how to do this, and it's pretty simple.
Secondly you will need to install a custom recovery such as ClockWorkMod or TWRP. I used CWM on my i747 and installed it using "ROM Manager" from the Play Store. It was amazingly simple and did the entire process for me.
Third you will need to choose the ROM you would like to try. There are a few different kinds, so happy hunting. I chose S3Rx and I love it. It's packed full of goodies and it seems that the Dev seems pretty good at answering any posts on his thread in this forum about the ROM.
Before you do any of that, you should verify what version your are running right now so you know what bootloader/modem you have, then go from there.
I just got back into this stuff myself and I love this phone. Good luck.