ATTENTION: For Lollipop root, please vist this thread its still EXPERIMENTAL root applied by me, and as such not gonna include here untill its been verified by users
I currently have the same phone on the same version as you, lollipop 5.1.1, and since it is not a well known phone, their isn't a one click install method. The only methods that I found, keep in mind I have not tried them and as such NOT held responsible for damages to your phone or Mentality
The only root method I have found would require you installing a custom recovery, in this case TWRP, and flashing the SU Binary (This enables us to have root) and then downloading SuperSU for the ability to grant root permissions to apps.
This following method will trip knox and thus making your warranty voided, and here are some facts about the problems with tripping knox
Rooting the Smasung xCover 3 (SM-G388f) KitKat
I haven't used this tutorial as I don't want to trip knox and as such cannot verify the integrity of this method.
Now to the good part!
- Download the newest Version of TWRP for this phone, Sansung xCover3, making sure to download the version with the .tar extension
- Download the newest ODIN version and install in onto your computer
- Download and the Phone USB drivers for the phone either, Via Samung Kies3 or from the ODIN webpage
- Download the newest SuperSU Binary and put it into the root directory of your device (Internal SD Card Memory)
- Install adb and read up on fastboot
- Make sure Phone is at least 80% charged and has USB Debugging turned on
- Turn off the smartphone
- Boot your device into Download Mode, to boot into Download Mode press and hold the "Volume Down + Home + Power" together till Download Mode is active. Once entered you will be seeing a warning sign asking if you want to continue, hit the "Volume Up"
- Open ODIN and then Connect your phone to your computer via USB Cable
- After connecting your phone to the computer, ODIN should say "Added"
- Once the device is detected by Odin, click on the button "AP" and select the .tar TWRP file you had download earlier, at the time of writing the current version would be twrp-3.0.0-0-xcover3ltexx.img.tar (9.1 Mb)
- Now, click on the "Start" button in Odin to start Flahing, Flashing usually takes 30-50 seconds to complete for the process of flashing the Samsung Galaxy Xcover 3. Once the flashing process in completed you will be able to see a green box with the words "Pass" in Odin. During this process the Smartphone will automatically re-boot
- Once TWRP is installed, move the SuperSU.zip file to your internal SD Card if not already
- Turn phone off
- Boot into Recovery Mode by pressing and holding down the "Volume Up + Home + Power" simultaneously until the TWRP Recovery mode shows
- Once booted into TWRP, Click "Install" and select the "SuperSu.zip", then Swipe to confirm the flash
- Reboot phone, if it was successful you should see the SuperSU app installed, if not install the app
- Verify root with the use of Root Checker, if it says root status verified then you have successfully rooted your phone, congratulations!
Hope I Helped, if you require any assistance you can contact me