Hello,
Very sorry for the delay.
I tried to reflash the firmware but the board is not even detected by the software. Tried from another computer on both Windows and Linux, still no sign of life.
EDIT : nevermind, I actually managed to reflash the DuetWifi firmware, also I reflashed the PanelDue's itself with its own firmware via bossac utility.
Everything seems to be functional, will test tomorrow with stepper and heatbed wired.
EDIT 2 : Everything is working as expected. My metamorph 3D printer project can now continue 🙂