[Galaxy S6 General] ServError:
So its been a long time coming, and I've finally compiled the files and time to make the long promised thread on flashing or modifying demo units. Most information herein will also apply to the G925X, granted that you have the corresponding firmwares.

If you find this compilation of information and/or files particularly useful, please consider buying me a beverage with the donate button, thanks!

Please do not direct link to my files. Send people to this thread instead. This prevents confused users and helps everyone involved.

Table of contents

Background info on the G920X

What can and can't be flashed

Returning to stock

Disabling retail mode

Creating a working Gear VR device while on a Demo Unit rom

Flashing to other variant roms

Special features like the fingerprint scanner

Available firmware files

Background info on the G920X / G925X

The G920X and G925X are live demo unit versions of the Samsung Galaxy S6 and S6 edge distributed internationally. They are almost full featured devices minus modem components and anything directly related to it. Although the bootloader allows for flashing of G920F / G925F files, several guides below offer a way to accomplish a nearly complete experience on the stock rom, which does not attempt to use the non-existent cell phone components but suffers a couple of minor drawbacks.

To keep it simple, the following features work, with caveats as noted -

Fast Charging - Stock G920X / G925X kernel may turn off charging around 70%. Will experiment with directly flashing other kernels on top and update this.

Gear VR - Works once following instructions below. Some power savings are evident and the phone does not seem to get as hot as the G920T/F/I and G925T/F/I, which is an awesome bonus. On stock G920X / G925X, there is an additional disclaimer screen when first putting the device on. There may also be a timeout where the currently open app closes if the device is not worn for a period of time. Need to do more experiments. Please test and report your own findings. You can always flash a G920F / G925F rom and compare.

Fingerprint scanner - Works after flashing 5.1.1 bootloader and rom and running software update, then flashing to G920F / G925F. Should also be able to root the stock rom and replace the settings apk with one from the G920F / G925F to get it working (possibly fingerprint packages as well).

32GB memory - Unfortunately this one is a bit painful. Samsung has started signing their PIT partition map files blocking us from flashing one with a reasonable hidden partition size (stock is 4gb). Until this is cracked there is no way to reintegrate this space into user data. In the meantime, if you have root you can edit the default mounting options for the hidden partition (change to rw) and create a symlink or similar to it in your userdata partition as a partial workaround.

What can and can't be flashed

All G920X / G925X and G920F /G925F roms should work, but you must remove bootloader files (cm.bin, sboot.bin, param.bin, modem.bin) to use G920F / G925F roms correctly.

If your G920X / G925X is currently on 5.0.2, you may have issues flashing or using certain features like fingerprint on 5.1.1 roms due to the old bootloader. It's recommended to update to the newer one using the files below, running the one available system update, and then proceeding with custom recovery and G920F / G925F flashing.

Returning to stock

Simple enough, for G920X, download the files below and use odin 3.10.6 or newer to load up all three. If you were on 5.0.2 or don't know, go into the odin options tab and check off bootloader update before starting. There is currently one update available that will download and install after you finish setting up the rom.

S6 Edge, G925X, see post here and use the files linked to revert to stock and obtain a newer bootloader - http://xdaforums.com/showpost.php?p=63762911&postcount=104

Disabling retail mode

There are two main apps and main passwords to deal with here, the admin password, 5444, and the master password, M729Q16K8546. After your system has been flashed and updated, enter the application called "RetailMode" and enter the admin password. Untick Play time scheduling (this setting may not stick) and then Service Enable. You must now enter the master password. Now exit the app and open "Samsung Retail Mode" and enter Customize Experience Contents, entering the admin password. Disable Retail contents protection (wait a bit for it and tap a few times to keep the device awake until it says that setup is finished), and, for safety, set the auto reset timer to the maximum timeout (3 hours?). Restart the app and enter Configuration Settings. Enter the admin password and disable the Factory Reset protection. Enter the master password once more and choose NOT to reset the device. Now tap "Delete hidden folders" and confirm. At this point you've finished with both retail mode apps.

You're now free to delete the folder in the main user storage called "Retail" or "RetailMedia". This is a big folder so you'll be happy to see it gone. If for any reason it wont delete, turn the retail contents protection from above back on, and after the reboot enable and disable service mode again. Now turn off retail protection (keeping the device awake) and delete the folder. If all else fails, delete if via your PC while the wizard is turning protection off.

Optionally, download Package Disabler Pro and disable the two retailmode applications used above. This will remove the notification tray icon as well as ensure that the services are not turned back on.

If at any point you factory reset the device, you will likely need to repeat this process.

Creating a working Gear VR device while on a Demo Unit rom

Currently recommend using a G920F / G925F rom instead if Gear VR is your primary use case.

You'll need to start by returning to a baseline stock setup with the files at the bottom of the post as directed above. Once you've booted into it and set up (samsung account sign in NOT necessary), check for system updates and let it update to the latest build. Disable retail mode as per above and delete its stray files. Download the Oculus Base package here - https://drive.google.com/file/d/0B4LLzOQW_EV4TzFRWmhqbEFNZkk/view?usp=sharing and extract all included APKs onto your phone. Install ALL of them, then open the Oculus app and sign in / sign up, then give the app a moment to recognize that you have all requisite APKs already installed. That's it! You're ready to slide the device into your Gear VR, accept the "extra" disclaimer page until a full disable method is found, and start the tutorial/download more apps. If you disable bloatware using package disabler, be aware that disabling some things will cause the Oculus app to fail to install its own apps.

Flashing to other variant roms

G920F roms and possibly others will flash and run just fine. The only preparation required is the removal of the modem, bootloader, PIT, and related partitions. This is mainly because Odin will fail, and not specifically due to incompatibility (though some pieces are in fact incompatible). G920FXXU3QOKN is provided below in the downloads with the extra files already removed and ready to flash, otherwise, continue on for instructions on modifying any other rom package. For any 5.1.1 rom such as those listed below, use the Return To Stock instructions first if you aren't sure that you're already on a 5.1.1 compatible bootloader.

To proceed, take an existing rom archive and remove the .md5 from the filename. Copy it to an available *unix machine and run the following commands -

tar --delete --file=[Filename here] hidden.img

tar --delete --file=[Filename here] cm.bin

tar --delete --file=[Filename here] sboot.bin

tar --delete --file=[Filename here] modem.bin

If a PIT file is included, delete it in the same way.

Now load the file up in odin and flash it over. Note that if you flash any non-stock kernel or recovery, it may work for up to one reboot, after which it will bootloop. Always be sure to test across several reboots before confirming that a specific rom or kernel works.

Special features like the fingerprint scanner

Confirmed working when flashing to G920FXXU3QOJQ, further tests to follow.

Available firmware files

G920XXXU1BOH2 - Install and use system update to get latest version, then disable retail mode as listed above

If your current/old rom was 5.0.2, download the bootloader (BL) first and flash it in odin as bootloader update (use the checkbox in options).

PIT file included in CSC.

AP - https://mega.nz/#!34EG2BCZ!m1WywuvOP3awZ2S9Sh5WIxmhzP-pOSs0wG7DYA-ehyI

BL - https://mega.nz/#!bxt3XBIK!-iH4gXYjQFVa3GDWFpv-W1Jg_Jxy0wR9kLigTGKX368

CSC - https://mega.nz/#!K91RgQjZ!wPtNc1RNTLTfcQRRa2OYNQuy40p3haMAC9R4ccggxKg

Special -

CSC without hidden.img - https://mega.nz/#!Cs9lASQa!4vKuuFabqRb3QeQA3PPZHq92IDg8iRr9fPmnbYqUtx0

G920F Rom with modem/bl/hidden already removed and verified working - G920FXXU3QOKN - https://drive.google.com/file/d/0B4LLzOQW_EV4ck5CeEF3MWpWUkk/view?usp=sharing (dead link, you'll have to make your own, sorry)

G920XZCU1BOI2 Files, only to be used if you specifically need them -

AP - https://mega.nz/#!Cx03WTTQ!-LyhT6baji6zdorVVMHE8S9cNJkFataORuWRNHqGFRs

BL - https://mega.nz/#!C8NShYya!dWxyz1VuX-4Jjws60f2M732FUlniKlA_dmkQk5HhDps

CSC - https://mega.nz/#!a1U1zZYQ!4qezYWoj16PylxU3_2kLFaafK_pJvSREI5r7bZ0zHOU