I have antminer S9 and the internet was disconnected for 1 hours and work again but I see one hashboard not working (the red led off)

I try do restart many time not work..

I check the board if burned or damaged but its fine and I don't see any damage .

I try connect this hashboard only but not working also .

Now I disconnect this hashboard and the others two board working good.

I've noticed when I connect and power on all hashboard ,the antminer Restart several times but two hashboard work good and the other one not working ( red led off)

how can resolve this problem ?