Quote Originally Posted by DPIN View Post
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.