1) Download the ROM
Download from sammobile.com (look for G900T, latest should be ~April 2017)
You'll need to make an account (free), and it's pretty slow, but there isn't really an option.
You might be able to grab the international version, but I haven't tried. I heard it's not compatible with some of the US locked versions, but the T-Mobile and AT&T versions were supposed to be exactly the same so they shouldn't have a problem. Also, it probably won't come with Wifi Calling.
2) Extract zip with `unzip` and then, extract the .tar.md5 with `tar -xf`
3) Download sgs2ext4.zip (google it:
forum.xda-developers.com/attachment.php?attachmentid=645192) and extract it
4) Run `java -jar sgs2ext4.jar system.ext4.img system.img` (and then do the same for cache).
5) Mount both images (`mount -o loop system.img system/` and same for cache).
6) Get `sec_csc.zip` from the cache folder and extract it.
7) Make a copy of the system/ mounted folder, chown it to yourself so that you can easily modify it later on.
8) Merge system/ folder from extracted sec_csc.zip with the system/ folder you created.
9) Copy boot.img and system/ into a new folder, let's call it build/
10) Get a copy of META-INF (update-binary is the important one) and also place it in build/
11) Use the updater-script from here:
https://forum.xda-developers.com/tm...pment/odexed-development-starter-kit-t3386186 and delete everything between "Symlinking and Setting Permissions" to show_progress (aka get rid of all of the set_metadatas).
12) Generate appropriate permissions (as described here:
https://forum.xda-developers.com/tm...pment/odexed-development-starter-kit-t3386186) and place them right after "Symlinking and Setting Permissions".
13) At this point, you should be able to zip everything up and install on your phone. This is a fresh full ROM with no mods and all the bloat.
14) Delete and don't forget to also remove set_metadatas that correspond to whatever you deleted or else the updater will complain that something might have failed. My old post (again:
https://forum.xda-developers.com/tm...pment/odexed-development-starter-kit-t3386186) also describes a couple of simple mods you're likely to make.
Note that if you disable selinux, you might not have to deal with permissions, but I think you have to modify boot.img for that, and I don't know how to do that. (Aside: Almost all ROMs posted not by me on this forum have selinux disabled. EG: if you install them, on every boot, it will say something about kernel not being selinux enforcing.) If you need more advanced modding, you'll need to deodex. I don't know how to do that and have never needed to. You'll have to look somewhere else for guides for that.
