1.5 megane 2002 wont start?

on the morning of recent heavy snow and frost my megane wont stsrt, when inserting card ignition lights just flash along with the door locks clicking uncontrolably. after reading about other common problems i checked that the earth wire was in good condition, i removed the control unit on the right hand side of the engine and left it to dry out. after refitting the problem still remains no different.