@dc42 thank you.
Do I have to do something about the process?

@droftarts I don't know if this can clarify something https://www.dropbox.com/s/cxmiagz20t1ytjx/5V%20Regulator%20Duet%203.jpg?dl=0)

@bearer
V_Fused and 12V Leds on

4 Leds on

@dc42 yes the jumper is in place and 24V PSU is supplying the board but the 5V led is off.

@bearer yes the 5V Led is off

When I try to connect my Duet 3 to my BLV Mgn Cube It doesn't supply the 5V neither SBC nor BLT, after that I plugged the usb cable to Duet 3 and both work fine, but the internal 5V doesn´t work, I Try to change the 5V jumpers configuration without success.
I think that my internal 5V supply is dead. Any idea to make it work?