Thread: Convert fenix 5S/5/5X Plus to D2 Delta S/Delta/Delta PX

There's now a much easier way to change firmwares by modifying the signature of normal update files. I've uploaded all necessary files here:
[Only registered and activated users can see links. ]

(Please note: Newer devices such as the MARQ or Fenix 6 series use encrypted firmwares that make it impossible to cross-grade the devices until the encryption keys are found.)

Spoiler: Outdated instructions from the very beginning of my research.

What you need

• a Fenix 5 Plus series watch
• Garmin WebUpdater
• latest D2Delta firmware matching your hardware
  
  • fenix 5S Plus --> D2 Delta S
  • fenix 5 Plus --> D2 Delta
  • fenix 5X Plus --> D2 Delta PX
  
  
• maybe RGN_Tool

Steps

1. Make absolutely sure that you have a compatible model.
2. Backup your data, note down your preferred settings, etc.
3. Make sure to have a shortcut to WebUpdater on your Desktop
4. Copy the downloaded D2 Delta firmware file to your desktop
5. (Might not be needed Use RGN_Tool to convert the D2Delta GCN file to RGN (DON'T TOUCH ANYTHING IN RGN_Tool!)
6. Put the RGN file on your Desktop as well
7. Turn the watch off and wait a few seconds
8. Take the watch in hand so that you can comfortably hold the START button for quite a while (don't press it yet) AND connect the USB cable at the same time
9. Drag the RGN file onto the WebUpdater shortcut and go to the device selection screen
10. Now hold the START button on the watch and connect the USB cable. Keep holding the START button for the whole time!
11. In WebUpdater click "Find device". The fenix 5 Plus with V3.20 should come up. Continue to flash the D2 firmware.
12. Once the firmware flash is complete, release the START button.
13. Watch the watch boot up as a D2 Delta.
14. Clear all data in Garmin Connect (or uninstall and reinstall) - otherwise the watch will still be shown as a "fenix 5 Plus" in GC
15. Repair the watch
16. Done.

For me, all my 3rd party apps, widgets, watchfaces, maps were still there. Only the internal stuff (preferences, activities, etc.) needed to be set up again.


Going back to fenix

To turn a D2 Delta or D2 Delta PX watch into a fenix 5 Plus (or 5X Plus), do the following:

1. Get a Beta firmware for the 5 Plus from before V4.20. I took fenix5Plus_356Beta.zip. You can find them here: [Only registered and activated users can see links. ]
2. In there, you'll find a folder "System_Backdate_v310". There's a gupdate.gcd in it. That's the one we need.
3. Now take a hex editor and modify the gupdate.gcd in the following way:
   
   1. at 0x1027 change 54 0B C8 00 3B 00 into 7C 0C C8 00 01 00 (turn fenix sig into D2 Delta sig)
   2. at 0xCF37 change 6D into 7E (correct checksum)
   3. at 0xCF5A change 54 0B C8 00 3B 00 into 7C 0C C8 00 01 00 (turn fenix sig into D2 Delta sig)
   4. at 0x8DED9E change 89 into 9A (correct checksum)
   
   
4. Put the file on your watch into the "GARMIN" folder
5. Install the update on your watch. (If it doesn't ask to do the update, you've probably made a mistake and the file isn't recognised. Start over.)
6. You've now got a fenix 5(X) Plus V3.20. Install updates to V5.10 or the current beta.