I recently bought a 1.6 cdti focus, on inspection i found that someone had jammed the Positive battery terminal with a screw to hold it in place (was arcing), anyways i serviced the car and it started up first turn of the key, then it died /stopped running

now it wont even turn over, the immobilizer light flicks constantly (16 Flashes/Can Bus Fault)

i checked all the fuses and wires for fault then used autocom to read the codes which were u1900 Can Bus Error, and a code relating to invalid security data on the instrument cluster

the dash simply says ----- i currently cannot connect to the ecu atall but i can connect to the instrument cluster etc

any ideas?