[Samsung Galaxy S7 Questions and Answers] Donnavarro:
here you go: basicly just the same but remember to flash s7 roms/firmware not s6.

Edit: /u/servili007 posted this thread on XDA developers forum which is probably a better guide. I'm not an expert so defer to that if it makes sense. /edit

In case you saw this thread a couple of weeks ago and thought you can get a GearVR capable Samsung S6 for cheap by buying a Live Demo Unit (LDU) here's some warnings:

It's a store display unit meaning it's likely used and abused.

There's no phone capabilities as the cellular antenna and SIM slot are removed.

The screen probably has burn in of some sort and has been on a lot.

It's not covered by warranty so you're getting it as is, and likely no return to the Ebay seller

The stock ROM automatically loads "Retail Mode" that's not simple to remove and it resets the phone

GearVR software likely will not load on it without effort.

If you understand the above, read what might be required before making the plunge.

First, watch this and write down the information he says to get: https://www.youtube.com/watch?v=n8LMyRqBViM

Basically you need to disable "Retail Mode" by installing a ROM that's not retail. Again, this probably won't work and will BRICK your phone, but you've been warned. This works for S6 and not the Note 4 which needs different passwords.

Go to the app drawer and open an app called Samsung Retail (not the Retail Mode program).

Go to Configuration Settings and enter the password 5444 to unlock it.

Then uncheck “Disable the factory reset” and enter the following password M729Q16K8546.

Decline the "Factory Reset" and instead turn your Samsung Galaxy S6 off

Boot into Recovery mode by holding down Volume Up, Power and Home button all at the same time.

Go to Wipe data & factory reset and press OK.

Now comes the fun part: Flash a stock firmware with ODIN. These steps I've got from here, here and here.

Go to sammobile and download the fimware you think it is the right one. This firmware which is a 5.0.2 version from New Zealand worked for more than one person

Extract the firmware file which is a 1.5gb tar.md5 file.

You will now have something like this G920IDVU1AOC6_G920INZC1AOC6_G920IDVU1AOC6_HOME.tar.md5

Rename it to something shorter like G920IDVU1AOC6.tar and be sure to delete the .md5 at the end.

Download the pseudo-Linux emulator Cygwin from it's home site here and install it

Move the tar file (G920IDVU1AOC6.tar) to C:\cygwin\home\''username''

Open cygwin and delete all the ''.bin'' files by typing the following commands (use up arrow to reload last command and edit for next command). Takes a few moments per command.

tar --delete --file=G920IDVU1AOC6.tar modem.bin

tar --delete --file=G920IDVU1AOC6.tar cm.bin

tar --delete --file=G920IDVU1AOC6.tar sboot.bin

Close cygwin. You can check if cygwin really deleted the bin files by opening the .tar file with winRAR.

Make sure the Samsung drivers are installed on your computer. Something you should verify ahead of time (before any of this) by seeing if you can access it from "My Computer" when it's connected.

Download the latest Odin3 v3.10.6 from here and unzip it (the link is in the signature block of the comment). Odin is a program for service stores to reload stock roms into units in maintenance.

Open Odin

Click on AP button and choose modified .tar file from step 7.

Connect your Samsung phone to the pc. Turn it on using Down Volume (not Up), Power and Home buttons. When you get the warning screen about loading up roms can be dangerous, press Up volume to accept.

On Odin screen, you should see the phone connect. Click "Start" and hope it works .... your s6 should boot a few times, and then start up like new, if not, try another fimware from another country from sammobile.

Again, the firmware that seems to work is a 5.0.1 and only if you remove the .bin files. The above worked for myself and I was finally able to load up GearVR. However, as it was a LDU there is burn in easy to make out. In addition it was an S6 with older firmware meaning it's missing out on some improvements.

Please note I don't make a habit of rooting smartphones or messing around installing images into hardware. As such, I probably spent way to much time searching around for the above, downloading a few roms and trying to get it to work before finding the correct path. Hopefully the above saves you some headache if you take the unadvised route of using an LDU for your GearVR.