How to Keep Root and Update AT&T S5 Active to OF2 Build

The AT&T Galaxy S5 Active received an OTA update with “Reactivation lock enhancements” and “Android security improvements” about a week ago with build number G870AUCU2BOF2. And as is the case with all security updates on Samsung devices, this one comes with an updated bootloader, and thus also breaks root access on the device.

The updated bootloader locks you down from any downgrade option to get back to 5.0 OC5 build, if need be. But thankfully, it’s possible to update your AT&T S5 Active to the latest OF2 build without upgrading the bootloader and also keep root access while doing that.

Developer muniz_ri over at XDA has developed pre-rooted stock OF2 ROM for the AT&T S5 Active which you can easily flash via TWRP recovery or FlashFire.

For those of you who haven’t tripped the Knox counter yet on their AT&T S5 active, installing the ROM via FlashFire would be the best way to keep root and the knox counter untouched.

We’ll guide you through the FlashFire way of installing the pre-rooted OF2 ROM in the steps below.

Download AT&T S5 Active G870A Rooted OF2 ROM Download G870A OC5 bootloader

Step 1: Flash Pre-Rooted OF2 ROM using FlashFire

Download and transfer the G870A_OF2_Stock_Rooted_ROM.zip from the link above to your AT&T S5 Active G870A.
Install FlashFire beta app from the Play Store. For this, join the app’s Google+ community first to get into the beta program, become a tester and then finally be able to download/install the app from Play Store.
Open FlashFire app, Grant it root access and Agree to its disclaimer note.
Now tap on the + floating icon on the FlashFire app » select “Flash ZIP or OTA” from there and then select the G870A_OF2_Stock_Rooted_ROM.zip rom file that we transferred to device in Step 1 above.
Keep “Auto-mount” checkbox unchecked under the “Options” menu and tap the right checkmark on the top-right corner of pop-up screen.
Now from the main menu, make sure to uncheck all options under the “EverRoot” option and set “Reboot” option to “Download” (Do this only if you’re NOT running the OC5 build already). But if you’re already on OC5 Lollipop, then leave “Reboot” option to “Normal” only.
Now tap the + icon again, select “Wipe” » tick the “Dalvik cache” and “Cache partition” checkboxes and untick/uncheck all the other checkboxes on the screen, then tap the right checkmark on top-right corner.
And now finally hit the Flash button on bottom of the screen to begin flashing.
Once FlashFire is done flashing, it’ll reboot your device. Now if you selected reboot normal in the Step 6 above, then that means you’ve the OC5 bootloader installed and thus your phone will simply reboot with the OF2 ROM without any issues. However, if you selected the Reboot option to download in Step 6, then your phone will reboot to Download mode and now you need to flash the OC5 bootloader using Odin. Get a PC.
Flash the OC5 bootloader you downloaded above via Odin 3.10.6 now, use the AP slot for flashing the bootloader. If you need help with Odin, check out this guide over here.
└ Just saying it again, flashing OC5 bootloader is only necessary if your AT&T S5 Active isn’t already on Lollipop 5.0 OC5 build. If your device is already on Lollipop OC5, then just reboot your phone. No need to flash the bootloader via Odin.