system does not activate the mosfet

[PaskuRt]

First of all, thank you for sharing your project, I have a problem with activating the mosfet, it does not open and when measuring the voltage between terminal D3 and ground it fluctuates between 0.8v when it should be on and 0v when it is off, I don't know what the reason why this happens and I have already tried several mosfets, I would appreciate if someone could clarify what is happening and what the solution would be, I am quite frustrated, thank you