Manually Updating Galaxy S3 Firmware I own a Samsung Galaxy S3 (SCH-I535), Stock ROM, rooted, running android 4.4.2 

For a while now, since updating to 4.4.2 through OTA, I have had horrible battery life. Android System constantly uses 20%+ of the battery life, and can get to upwards of 40% for no apparent reason. I made an attempt to factory reset, but I messed up the backup process, and lost a lot of data. I decided to root the phone and explore other options for saving the battery. The factory reset hasn't worked, and although using some root-worthy apps like Greenify and others, nothing has helped significantly.

I asked a question on Android Enthusiasts a while back about this battery issue, and a user replied saying he experienced the same issue, but he fixed his by doing a manual install (through a PC connected to the phone with USB). Apparently the OTA update can get messed up somehow. I want to try this but I'm running into some issues.

When installing the Samsung Desktop Update Utility (or whatever it's called), it installs, but will not run. As soon as I run it, WerFault.exe also runs, and then they both close a few moments later. So this option is out.

Now, I moved on to Kies. I installed this program since it was said I could update this way. But, I see a lot of people saying that Kies is unreliable. The alternative is a program called ODIN.

TL;DR-- 


What could my issue with the Samsun Update Utility be?
Is Kies a reliable way to do this process? Or will it brick my phone as I so often see?
Is ODIN a reputable and competent alternative? 


Any help is appreciated, and I can provide whatever extra information is needed!
Is Kies a reliable way to do this process? Or will it brick my phone as I so often see?


I only install Kies for the USB drivers.


  Is ODIN a reputable and competent alternative?


I need Kies for ODIN to detect my Samsung Device. So yes, ODIN is a reliable alternative.

As from what I read, you already messed up your files, so there are few files left to backup. Backup those files.

Method 1:

You can do a manual flash. Guide

My steps:

(Disclaimer: Do at your own risk.) 


Download a Stock ROM (.tar or .md5 file) for your Samsung S3 and ODIN 3.07 (I frequently use).
Install Kies. Make sure that you have installed Kies. Then terminate all processes that have linked to Kies.

heck your Task Manager > Processes > Look for processes with the Kies name in it (e.g. KiesTrayAgent.exe). 
Make sure your device is charged, around 80%-90%. Power off the device.
Boot into ODIN mode (press and hold Volume Down + Home + Power keys together). a new screen will show up. Then press Volume Up key.
On your PC open ODIN, then plug-in your device. There will be change in ODIN, like this




Follow the options on the picture. Do no change anything. Then click PDA and locate your Stock ROM file.
Hit Start. Let the devices do the work. Do not power-off and/or interrupt the PC and Device as  this may cause the device to get brick.