fortiweb boot and console connection problem

hi every body,

i'm using fortiweb 1000D in an enterprise network configured to work in transparent mode.it was working properly but suddenly two days ago it stopped responding to web ui connections and i could'nt connect it via ip address.So i tried to connect it via console port and i saw that i can't stablish any connectin and it did not respond to console connection.Is there anyone can guide me to reset factory setting or load firmware via hardware phisically and without cli and web ui access?