Ultra96-V2 can not start

After switching on the power, I pressed SW4 button and the board couldn’t start. The phenomenon I see is that a green LED light (D3) flashes and a blue LED light is on, but the yellow light (D9) next to the blue light is weak and unstable

I can’t find the wifi signal. Also, I used active miniDP to HDMI and then HDMI to VGA to monitor, the monitor showed no signal. I can’t find the cause of the problem. Does anyone know how to solve it?