Hello, when the motherboard is connected to the adapter, the board automatically turns on the signal lights and the fan rotates constantly, when the button is pressed, the board turns on and works normally, but when it turns off at the button or is turned off from the system, the board automatically turns on the signal lights and the fan again. It even turns on the signal lights and the fan even when the KBC is removed. Has anyone had a similar problem?

Нет, не было такой проблемы, но начните со схемы, с проверки входных ключей на предмет пробития.