M900 - MAC address lost

My M900 can't be used from last week.
The first symptom was the base station lost from all the M25 connected on it and was unable to login in the M900 UI and ping it, also after 2 restart.
Then, I factory reset the device and finally I see it in the DHCP server with a strange MAC address: "000012000000".
After that, I tried to:
configure the SIP server = no chance,
register an M25 = no chance,
update the firmware = no chance.
I realize from the system info some missing information like the wrong MAC, so I think I need your help to fix the problem.

I've bought this device this year, so it must be under warranty.
What's your suggestion?

Thank you,

Samuele