[Galaxy S6 Edge Q&A, Help & Troubleshooting] cyphol4:
Welcome.

After two days of sweating trying to understand all the guides and tricks as a complete newbie, I realized that some things are easier than they seem but requires certain knowledge to pull off.

I softbricked my device after my first attempt of rooting but after two days total, I managed to get everything working. The point of this guide is to be as thorough as possible because a lot of the guides out there, no matter how well they were made, some things still did not make sense to me as a newbie and I intend to make it a lot clearer in this guide.

Please understand that my knowledge is very limited, but I am going to explain very thoroughly step-by-step how I managed to update my firmware using Odin, Uni root and TWRP. I will also do a brief explanation of how to use TWRP to install a ROM as that was my goal from the beginning.

Note: I can only assure you that this worked for me with the firmware version, root and TWRP that I used. I cannot guarantee that this will work for you at all, and you should make sure to read and understand the risks about flashing and rooting your device. I take no responsibility if you brick your device, please continue at your own risk. Also note that you may or may not lose your data depending on what you do so I suggest you backup all your files somewhere else if you want to save your data. YOU WILL VOID YOUR WARRANTY USING THIS METHOD.

Firmware

It is important that you have a supported firmware for whatever root you are chosing. I have a SM-G925F and here is the link to all the newest firmwares.

http://www.sammobile.com/firmwares/database/SM-G925F/

If you have a different model, you can change the last section of the link "SM-G925F" to whatever model you have, for example ".../database/SM-G925T/".

For this guide I am using 5.1.1 G925FXXU3COI9 (Sweden).

Drivers & Odin

Download and install the necessary drivers for your Samsung Galaxy S6 Edge provided in the link below.

https://www.dropbox.com/s/jze4q58cspwnjwh/SAMSUNG_USB_Driver_for_Mobile_Phones.zip?dl=1

Download latest version of Odin provided in the link below.

http://odindownload.com/download/Odin3_v3.10.7.zip

Testing your connection/Debug mode (MANDATORY)

Enter settings on your device, scroll to the bottom and chose "About device".

Then tap on Build number until you have unlocked "Developer options".

Go back a step and you should now be able to see "Developer options". Enter it and find "USB Debugging". Activate it.

Connect your device to your PC. If this is your first time doing it you will get prompted on your device to allow your PC access. Please tick the box and allow it. Now start Odin and make sure you have a COM connection.

We now know that your device has a connection with your PC and can start the firmware flash.

Unlocking Bootloader

If your bootloader is locked, you should be able to see a setting in "Developer options" that can be called "OEM Unlocked", "Unlock OEM" and so forth. You will want to make sure that your OEM is unlocked, otherwise you will most certainly fail.

The most common question for bootloaders are the ones who can't find this setting and what that means. If you can't find the OEM Unlock setting, then your bootloader is probably already unlocked. And I can confirm this as I did not have this setting and have a perfectly working 5.1.1 rooted with custom ROM.

Flashing firmware

Make sure you have enough battery, I usually keep my phone around at least 80% when flashing.

Turn off your device completely, "Power off". Now hold Volume Down + Home button + Power button until you get a screen with "Warning". Click 'Volume Up' to enter "Download mode". Make sure Odin finds your device while in "Download mode" by checking the COM connection.

Now unpack the firmware you downloaded. You should now have a "FIRMWAREVERSION".tar.md5 file.

Open Odin, click the "AP" button and navigate to the "FIRMWAREVERSION".tar.md5 file you just unpacked. Please allow Odin to load the file and wait until the log says "<OSM> Leave CS..".

You can now click "Start" and let Odin write all the files. Do now touch anything during this process. When it is done, if you have done everything correctly, it should become green and say "PASS!". At this point you have successfully flashed the firmware to your device.

Rooting

Make sure you have a supported firmware before attempting to root. If you have flashed your device accordingly, this root should work perfectly. Make sure your device is supported and then download the Unikernel "ODIN FLASHABLE".

http://xdaforums.com/galaxy-s6/samsung-galaxy-s-6--s-6-edge-unified-development/kernel-stockmod-kernel-t3100395

We are now going to do the exact same process as above, but this time using a different file. Put your phone in "Download mode", connect it to your PC and make sure you can see the connection in Odin. Click the button "AP" in Odin and navigate to the Unikernel.tar file.

Click start and wait for Odin to complete the process. It should become green and say "PASS!".

Your device will reboot and you should now be rooted if you have done everything correctly.

TWRP

TWRP is a custom type of recovery that can be used to do a lot of things. Please read about TWRP here: https://twrp.me/about/

To install TWRP with Odin, your device needs to be rooted. Here is how you do it.

First, make sure you download the supported version for your device from the link provided below.

http://galaxys6root.highonandroid.com/cwmtwrp-recovery/

I have a SM-G925F and I downloaded the .tar file shown on the picture below.

Again, repeating the steps from above. Put your device in "Download mode", connect it to your PC and check the connection in Odin.

Click "Start" and wait for the process to "PASS!". You should now have TWRP Recovery installed properly.

To access TWRP enter your phone into "Recovery mode". You do this by turning off your device completely and starting it through Volume Up + Home button + Power button. From here, you can do a lot of things but most importantly you can install custom ROMs. Always make sure to check the installation guide for the ROM you want to install but basically you copy the ROM to your phone memory, chose "Install" in TWRP and navigate to the ROM.

I hope this helps people who are impatient to learn all the details and just want to be a user. The problem with this is that if something goes wrong, you might not have the knowledge to fix your problem instantly and might have to wait for responses on the forums. Usually if your phone is Softbricked or stuck in a bootloop, you can enter "Download mode" and flash a suitable firmware from the links provided. Please let me know if you still have questions and/or don't understand some of the steps and I will adjust accordingly. Good luck!