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I started this community to share my experiences with various Android devices. Hopefully, this will help others looking for solutions. Granted it is only covering the few devices that I own, some of which are very old now.

This site will cover these devices:

Galaxy S3 I9300
Galaxy Mega 6.3 I9200
Lg G3 D855

Rooting the Galaxy Mega 6.3 I9200 (melius)

There is a lot of old information around for this device. Some of it is wrong and some is part right and most of it doesn't have the files used. But after trying combinations, this is what worked for me.

There are two options, one to root the phone and stay with the Stock ROM, and two to root the phone and install a custom ROM. As of May 14, 2017 the only custom ROM I could find is Revolution Remix Nougat.

All of these steps assume you are currently on Stock 4.4.2. If you need stock Android you can get it from https://www.sammobile.com/firmwares/galaxy-mega/GT-I9200/. Download any ROM for your region and install it using Odin.

NEEDED FILES

Download the latest Odin (as of May 14, 2017 it was Odin3 v3.12.3). https://drive.google.com/open?id=0BxMDe1n70DFlNTRUS1VDTUp0V2M

Download Auto-Root for the I9200. https://drive.google.com/open?id=0BxMDe1n70DFlMHZUNEZPeDRwVE0

Download TWRP twrp-2.6.3.0-melius.tar (this is the official TWRP recovery but you may not need it, I did and I could not install any version higher than this, all the others failed) from here - https://twrp.me/devices/samsunggalaxymega63.html or from https://drive.google.com/open?id=0BxMDe1n70DFlbFdablM1SWJzc0k.

To flash the custom Revolution Remix ROM you can't use the Offical TWRP recovery because it needs a tweek to work with the custom Revolution Remix ROM, so get the latest here https://forum.xda-developers.com/galaxy-mega/orig-development/rom-resurrection-remix-n-5-8-0-t3507216 - look for the downloads or https://drive.google.com/open?id=0BxMDe1n70DFlbFdablM1SWJzc0k.

Download the latest Gaaps from http://opengapps.org/ - select ARM, and 7.1 if you are installing the custom ROM. Don't do this if you are staying with the Stock ROM.

STEPS TO ROOT

If all you want to do is root your Stock ROM, then you need Odin and Auto Root.

If you are going to install the Resurrection Remix ROM you can probably skip this step because the ROM has its own custom root.

Extract GT-I9200-4.4.2-Auto-Root.rar and Odin3-v3.12.3.rar and put them in the same folder.

Put your phone into Download Mode by pressing and holding the Volume Down + the Home Button+ the Power Button until the Download warning is displayed then release the buttons and press the volume up button.

Next connect your USB cable to the phone and PC. Then start Odin.

Click on AP and search for the CF-Auto-Root.tar. Under Options in Odin make sure that only Auto Reboot and F. Reset Time are checked. Then press Start, it should only take a moment to flash and the device will reboot and CF-Auto-Root will update the device and then reboot to your Stock ROM. Then open Google Play and search fro SuperSU and install it. Your device is now Rooted!

STEPS TO INSTALL Resurrection Remix

You need Odin, TWRP, and the Resurrection Remix ROM.

Extract Odin3-v3.12.3.rar and put them in the same folder.

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