X3SG how to factory Reset

[AWS2P]

Hi,
on a location behind a SBC a Fanvil X3SG phone is no more able to connect to pbx, on phone display I get only a progress bar staying there for ever.
As the phone is no more seen on pbx side, no way to catch it with its GUI, so I tried to factory reset it but with no success until now .
I tried to restart phone with # key pressed hoping for a never coming mode to engage second set of key like * # 1 6 8 to factory reset the phone.

What is the real key sequence to proceed a successful factory reset, I have got same problem on X4U model with same problem to do a factory reset.
Is it me doing wrong or key process for these models is no more reacting like explained everywhere on 3CX docs, and lots of tutorials.

 

[JohnS_3CX]

I don't know if it could be related but we have 2 X4 that refuse to upgrade firmware. The PBX sends the NOTIFY and the phone reboot, but they never download the firmware even though it is downloaded on the system.

Reboot them and try again. If they still fail to do it, try them on a local PBX (if you have one for testing).

On a local PBX you can run a capture and see the http commands to confirm if the phone is trying or not, and what happens when it does