Are you sure the ECU is being powered? I have just been through something similar on a 155 - ECU scan would not connect. The car cranked normally, but did not fire. No fuel pump or sparks. Turned out that the relay supplying the ECU had failed - suddenly while the car was idling. Once this was fixed, ECU scan connected and the car worked. You'll need the wiring diagrams for the car to pin this down, I don't have them for a 156.
Also - if the car just cranks, is the code light going out? Could be the immobiliser - if there is a a little "code key" illuminated, then start looking at the antenna around the key barrel