[Android General] Droidriven:
It's H1, cool. You'll be amazed how easy this is. You'll be doing all of this, except downloading your ROM and Google apps, directly from the device.

Use PC to download these files then connect the S3 to PC and copy them to external SD card.

1) download this file, it's the last release of Octos 6.0.1 marshmallow(there is also 7.1.1 available but I haven't used it so I can't verify stability), it's a very good ROM, I used it for over a year on this device, store it on an external SD card as a file by itself, not in a folder.

https://basketbuild.com/filedl/devs...lease/d2vzw/OCT-M-R3-6.0.1-20161025-d2vzw.zip

2) Go to http://opengapps.org/, select:

ARM

6.0

Micro

Then click the red download circle. This is the Gapps(the stock Google apps) package that you need to flash with the ROM, they are flashed separately because they can't be included in the ROM file. Place this file on the SD card with the ROM file, as a file by itself, not in a folder.

Now, on the device:

1) Go to system settings>security> unknown sources and enable it (it will prompt you warning that it can be dangerous to install apps from unknown sources, you only need it to install the Towelroot app to root on the device).

Also, go to system settings>about>build number, tap it repeatedly until you see the message saying you are a developer, this unlocks developer options, go back to system settings>developer options>USB debugging and enable it.

2) using the devices mobile browser, go to https://towelroot.com/ and tap the big red lambda symbol to download the Towelroot app. (you might get a warning about the site being dangerous, don't worry, this is because Google sees the Towelroot app as a virus because it can be used to modify your system partition which is actually what you want, you will be removing root when you're done but right now you need it)

3) Drag down the notification in status bar for the app that you downloaded, tap on it and install the app, once installed, open it, tap the "make it rain" button, you'll be rooted in about 10 seconds, you can uninstall the Towelroot app now, it isn't needed anymore.

4) Go to PlayStore and search for "SuperSU", install it, open it, it will ask you to update binaries, when it asks which method, choose "normal", reboot the device if it doesn't do it automatically. (if you get a prompt asking you to grant superuser permission while doing this, grant it, this is what allows you to write to /system)

5) when the device reboots, go to PlayStore, search for "TWRP Manager", install it, open it(grant superuser permission if prompted at any time while using TWRP Manager)

Now you're ready to follow my guide, starting from the ***FLASHING WITH TWRP MANAGER*** section.

When you get TWRP installed, skip to the ***BACKING UP YOUR STOCK ROM** section and continue from there, you can ignore all the stuff about SIM and APNs. I recommend doing a clean install of your ROM, coming from stock to custom ROM usually causes a bootloop, clean install avoids this. After you get your backup created, read the troubleshooting section in post #2 of my guide, it explains how to perform a clean install, just make absolutely sure that you create your stock backup before you do it. You will be wiping the operating system and everything on the device out before installing the new ROM, don't worry, everything is still safe in the backup you created. This is similar to wiping a PC and reinstalling Windows, the device won't boot without OS so you must flash the new ROM before trying to reboot the device. Sounds scary but it's really simple.

https://xdaforums.com/galaxy-s3-verizon/development/guide-to-flashsetup-sim-apn-cm-cm-based-t3351290

After you get the device signed in with Google, you can go ahead and remove root permission from the device. To do this, open the SuperSU app, open its app settings menu, find the option to "cleanup for unroot and uninstall", it will remove root. Reboot the device and you should be done. You're ready to setup for the grandson.

Just make sure you charge the battery to full before you start flashing the ROM and Gapps, if the battery dies before it is finished, it will damage the device and it's a headache to fix yourself.

If you have questions I'm here.

I DO NOT PROVIDE HELP IN PM, KEEP IT IN THE THREADS WHERE EVERYONE CAN SHARE