[Galaxy S III I9305 (4G LTE + 2GB RAM) Q&A, Help & ] Chevan94:
Hello!

I'm new to posting to this forum, so you can call me a noob. I'm sure I am a noob, I'm sure I did something wrong. I was just a customer for the time when GingerDX development started for Xperia X8, my previous phone. I'm not a dev, but I know know to flash stuff and what to avoid or do with care. If this thread is in the wrong section, then sorry, please move it where it should be.

Three months ago I got my new shiny GT-I9305, version for Poland (distributed by Plus), and as I did with my X8 previously, I decided to root it and dive into flashing many custom ROMs.

I made the EFS backup following lyriquidperfection's thread (http://xdaforums.com/showthread.php?t=1946915), so my IMEI and NV items are safe and secure. I also did a backup of a stock 4.1.2 ROM.

I was using many different ROMs and kernels from XDA, both based on CM10.1 and Official Samsung ROM. I had PhilZ Touch 5 recovery installed. Everything worked fine, until I noticed something strange:

After I flashed an unofficial port of SlimBean to I9305 (http://xdaforums.com/showthread.php?t=2297679), and Yank555 kernel for CM10.1 based ROMs, I noticed that in "About phone" section, my phone is shown as "GT-I9300", but I'm 100% sure I flashed the file that had I9305 in the filename, so it couldn't be my mistake. I didn't buy I9305 for 4G, but for 2 GBs of RAM, so I couldn't test if LTE was working (My carrier is T-Mobile.pl, which doesn't have 4G in Poland yet), but I didn't see the option to even search for LTE networks available. I didn't care much about that, since everything else was working just fine.

I decided to flash the previous ROM I was using - Sentinel Rom, because I found the bug with GPS and I wanted to see if the same happens in that rom. I rebooted to recovery, but... I couldn't install the package. It was all giving the "set_perm some changes failed (status 7)" error all the time. The same happened when I tried to install LiquidSmooth for i9305. I just couldn't flash any 4.2.2 ROM, I was able to flash a kernel just fine.

I decided to flash Ripper Rom instead. It installed with no error, it just said: "Root access is missing, root the device?" so I simply said to root it. But the phone couldn't normally boot. It stayed for a while at the "Samsung Galaxy SIII GT-I9305" splash screen with the little red exclamation mark in the top left corner, then it kept rebooting back to recovery. I had no idea what's going on. Wiping data/cache/dalvik cache/system didn't help at all. The only way to make the phone working again was to recover SlimBean from Nandroid backup I had done previously. Sadly, I had no Sentinel Rom backup. Deleted it. Shame on me.

I successfully restored Stock 4.1.2 rom from the nandroid backup, but I still couldn't install any custom ROM via recovery because of the same error.

After several tries to install different ROMs, redownloading everything and going through a lot of stress I gave up. I installed TriangleAway, reset the flash counter and, through Odin, flashed tar.md5 of the stock ROM delivered by Plus, downloaded from here: http://goo.gl/SMWEha. I installed a version build XXBLL3, which later updated itself to XXBMB4, and baseband updated from XXBLL3 to XXBMA2.

Right now, I have Official, Stock 4.1.2 ROM from Plus, with Baseband version I9305XXBMA2, build number JZO54K.I9305XXBMB4 and stock kernel.

What Download mode says:

Product Name: GT-I9305

Custom binary download: No

Current Binary: Samsung Official

System Status: Official

Now to the questions:

Why this started happening? Was the reason the wrong model of the phone in "About phone", hence installing SlimBean?

When I flashed the stock ROM, does it mean that I'm fully back to stock, with everything removed? Does it mean that my phone is like I got it from the box, with warranty? The recovery seems stock as well.

Can I root it again? If yes, how to do it safely, to not make something like that happen again?

Baseband got updated. Does it mean I have to make an EFS partition backup again?

Sorry if I ask too much, but I'm a very careful person, and I want to know everything before I start doing anything risky with my smartphone.

Thanks in advance.