Fiat cinquecento Sporting does not start after kerb contact!

Hello… Drive – actually, when he is driving – a Fiat Cinquecento Sporting BJ 1996. Since last week he does not jump after a little contact with a curb anymore. ADAC gave me the hint to try it with the inertial switch/crash switch. After a long search also found, but no… ignition goes – otherwise no reaction. Battery light on. For the first time after this small crash I have seen the code key symbol in the display… yellow on, and immediately goes out again. Battery symbol lights up, injection nozzle light on, oil light not… After many attempts the ADAC measured, and thought it could be 80% the combi relay (fuel main relay)… New ordered, built in – nothing… I’m in despair!!! Have no idea even of cars, but work in a forwarding agency, surrounded by professionals. But also here no one can help… Have WFS – two keys and code card. How to enter the code – for the Fa ll, that it might be because of it? How do I recognize that it is the control unit? At the moment there is no / little money! Can’t therefore order a workshop for good luck, which searches around senselessly and writes me a high bill for nothing… HELP!!! In advance already many thanks Mariechneneidi