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

[mbirth]

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Spoiler: Outdated instructions from the very beginning of my research.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

[mbirth]

I've now added the procedure to turn a D2 Delta (back) into a fenix 5 Plus. You can also use this to convert a D2 Delta to a fenix 5 Plus. Or D2 Delta PX to fenix 5X Plus.

[DPIN]

Thank you so much for posting the procedure. I followed the instructions carefuly on my D2 Delta PX (using the 5xplus beta 356) but ran into an issue. After copying the modified gupdate.gcd file, the watch did update, but once reboot was complete, it remained a D2. Any advice would be greatly appreciated!

Could it be that the PX sig is different than that of the regular D2?

[mbirth]

Make sure to use the gupdate.gcd from the "System_Backdate" folder. (Only those have the "Downgrade"-flag set and I'm pretty sure that's needed.) The one for the fenix 5X Plus should be the same as the one for the fenix 5 Plus. The firmwares (and signatures) for D2 Delta and D2 Delta PX (also fenix 5 Plus and 5X Plus) are exactly the same - they only have different SensorHub firmwares which is installed separately.

When the watch asks to install the update, maybe keep the START button depressed for a minute or two and see if that makes a difference.

I could also send you the file I've used. Should work for your PX as well.

[DPIN]

Thanks again for your time and attention - it's really appreciated.
Regretfully I'm still experiencing the same issue (update runs, but watch remains on the PX firmware after restart). Holding the Start button pressed did not make a difference. I ran through the steps with a clean download and another hex editor.
Would love to give it another try with your file if your kind offer is still open.

[mbirth]

Sure, here is the file:

[Only registered and activated users can see links. ]

I'm not sure if one of the 100 other things I tried before that last file did anything in the process. Or if it only works on original fenixes, not Deltas.

I'm afraid if that doesn't work now, I'm out of ideas. I'd probably have to experiment with a real D2 Delta to find a way then. But AFAIK, Garmin will release the 4.00 update for the D2 Delta soon. That should bring the newer bootloader with which you can easily flash the other firmware.

[DPIN]

Many thanks!
Alas, this did not work either... perhaps, as you suggest there are additional subtle differences not yet accounted for. I'll await the 4.0 update and post if there's progress.
Thanks again!

[mbirth]

@DPIN Guess what, Garmin just released firmware 4.00 for the D2 Delta series. Could you please update to that and once it's updated, please power off the watch. Then hold the top right button ("Direct to"/"D2") and switch it on with the Power button, but KEEP HOLDING the D2-button. It should show the blue triangle but not boot up as long as you keep pressing the D2-button. Once you release the button, it should boot up normally.

Please, tell me if that works on the D2 with V4.00.

[DPIN]

Thanks for the heads up!
It appears that my share of trouble is not done yet... I can't seem to be able to update to v4.0 - whether by a sync with Connect, running "Web Updater", or even copying the v4.0 gcd file directly to the watch.
The watch does prompts me to update, and after selecting "Install Now" it shows "Installing System Software Update", then reboots - but the version remains 3.0. (e.g., Menu->Setting->About" shows "Software Version 3.00". Also, none of the new menu items described on the V4.0 release notes are visible).
Once I get it sorted out - I will definitely give it a try. Just to be certain - I assume your suggestion is to copy the patched "5x plus" file after the upgrade to v4.0, and before carrying on with the procedure suggested - right?

[mbirth]

Once I get it sorted out - I will definitely give it a try. Just to be certain - I assume your suggestion is to copy the patched "5x plus" file after the upgrade to v4.0, and before carrying on with the procedure suggested - right?

If you can force preboot mode by holding the D2-button (or START button, upper right one), you should be able to simply flash the normal f5X+ firmware without any patching. Maybe convert it to RGN first, but I'm not sure if that is needed. Then install WebUpdater and create a shortcut to it on your desktop. Drag the firmware on it and connect the watch in preboot mode (turn off watch, disconnect from PC, press+hold Direct-To-button and connect to PC while keeping holding the button), keep holding the button for the whole procedure and flash the firmware.

If that works, you can use the same way to go back to the D2 firmware. Since the D2 firmware is "older", I'd suggest doing a master reset after going back.