[Galaxy S6 Edge+ Q&A, Help & Troubleshooting] mangus99:
Solution!

OK, so after much trial and error, I have successfully rooted my 9280 and installed a working Google Play store. I'll outline what I did and post file names for the specific files I used so there's no confusion. I will say that, surprisingly, the Google Play store updated itself to the new version and continues to work, though periodically some app will install and invoke Google Play Services, which, if installed, continues with the loathsome "Unfortunately Google Play Services as stopped." This is easy to solve by simply going into settings>Applications>Application manager>Google Play Services>Uninstall - then all is well again. I've found that despite many applications popping up a prompt to install Google Play Services and that they are needed, most of those apps will run anyway (sadly NOT HBO Go, YouTube or Hangouts, but Netflix, Hulu, Google Maps, Google Photos and gmail account through email app (not gmail app) all work fine) - just click anywhere else on the screen to dismiss the prompt.

Tools and Apps you'll need:

1. Odin 10.3.7 or 10.3.6 - Windows (I could not get JOdin to work as download or web app with Yosemite) - generally comes in one of the bundles you'll download below, such as CF-Auto-Root

2. Firmware version G9280ZCU2AOK6_G9280CHC2AOK6_CHC (sadly used sammobile.com - go to bugmenot.com for shared login to enable downloads - but they still take FOREVER - like 2-3 hours)

3. CF-Auto-Root-zenltechn-zenltezc-smg9280.tar.md5 (https://download.chainfire.eu/798/CF-Root/CF-Auto-Root/CF-Auto-Root-zenltechn-zenltezc-smg9280.zip) - comes with Odin bundled

4. SideSync_4.2.0.15125_9 (download mac or windows version through samsung site - I used Mac version); download android app through stock galaxy app store or through Google Play store

5. CROM Service app v 1.0.4 (http://xdaforums.com/attachment.php?attachmentid=3270074&d=1429412423)

Notes:

1. SideSync will allow you to transfer files (apk files) into the device storage (it will go into a SideSync folder - browse using the system's built-in My Files app). With the My Files app, you can navigate to the SideSync folder and install an apk you moved there by clicking on it.

2. If you need apps before you can get Google Play store installed, use apkmirror.com to download to desktop, then move them to phone using sidesync and install as described in Note 1.

3. "Flashing" - put the phone in Download mode - Hold Volume Down, Home Button and Power Button together until you get a blue screen with a triangle warning (!). From here, Volume Up enters Download Mode. (Volume Down simply exits/reboots).

4. "Recovery Mode/Clear Cache" - Enter recovery mode by holding Volume Up, Home Button and Power Button Together *during a reboot* until you get the recovery screen (Press power button, select reboot or, if nothing else, use method to enter download mode, but press Volume Down at the Warning Screen to reboot instead of Volume Up). To clear cache, use volume buttons to scroll to "wipe cache" and press Power Button to confirm. Once complete, Reboot System.

5. Clear Dalvik Cache

So now for the steps:

1. Enter developer mode. Go to Settings>About Device>Software Info. Click on Build number repeatedly until you enter developer mode. then go to Settings>Developer Options [a new menu item just above About Device] and enable OEM Unlock and USB Debugging.

2. Download and install SideSync to phone and desktop. Establish connection.

3. Download and install CROM Service apk (#5 above). Unlocks phone.

4. Download stock firmware (#2 above). Flash to phone using Odin. (select the firmware file in the PA button (second from the top).

5. Reboot (should happen automatically)

6. Download CF-Auto-Root and flash to phone using Odin. (more detailed instructions here: http://www.skyneel.com/2016/01/root-samsung-galaxy-s6-edge-plus-sm-g9280.html) -- BUT -- uncheck the "auto-reboot" box under Odin options. Once install is complete, enter RECOVERY MODE by rebooting (start to go to Download Mode by VolUp-Home-Pwr, then VolDown instead to *reboot* and immediately press and hold VolDown-Home-Pwr to get to recovery - for me, this started the auto-root process but DID not install SU (not sure why, but this is what worked for me in the end). Don't allow the phone to reboot again - once it starts, hit the Recovery sequence again and clear cache.

7. Allow the phone to actually reboot.

8. Download Google Play v 3.10.14.apk, (com.android.vending-3.10.14.apk), Google Services Framework (googleservicesframework_1348820903272.apk) and Google Login Service (I got them as a single package through Open Gapps). Move these files to your phone via SideSync. Do not do anything with them yet.

9. Download and install Root Explorer to your phone (via apkmirror if needed).

10. Download and install Market Unlocker to your phone (via apkmirror if needed).

11. Run Root Explorer. Navigate to each of the three google files and move or copy them into your phone's system files at \system\priv-app (you can get to the root folder through the heart symbol - favorites - and back to storage the same way).

12. Using Root Explorer, click-hold each of those files and select "permissions" - uncheck write for group and others so that each now has rw-r--r-- as its setting.

13. Using Root Explorer, delete your dalvik cache by navigating to \data\dalvik-cache and deleting all files and folders in there (I actually moved each of the three folders to my device storage to be on the safe side).

14. Reboot directly into recovery mode. Wipe system cache. Reboot.

15. System startup will take awhile as it installs apps from your priv-apps and loads things into dalvik-cache.

16. Run Market Unlocker and choose a market - I used United States (test).

If all goes well, you're now up and running. Again, if play services starts cropping up, go into settings and uninstall.

I'm not sure all these steps were essential, but I'm running now. I should note that I still don't have SU (SuperUser app) on the phone. I may try installing that to see if it allows me to run play services without problems.

On a final and likely confusing note, I manually edited a number of the files in \system\csc to delete or alter settings that looked problematic (enforce_policy_chinanationalsecurity>TRUE<; disable_google_>TRUE<; etc. and to change "sales code" to AWS, region to "US", country to "USA" and language to en_US or "english" depending on syntax and structure -- I changed TRUE to FALSE and vice versa as appropriate, or sometimes deleted the entire string from the file - it will create a backup when you save and exit for safety - and I also moved those over to my computer for future use and tinkering). I had never done any of this before and had no idea what I was doing. I accidentally deleted the stock keyboard and had to use SideSync to enter text until I could download a new keyboard apk (swype, google keyboard, SwiftKey are all good options).

That's it, follow at your own risk!