i have a 04 1.4 petrol 307. Only 19k miles. Got home the other day locked the car and came out 3 hours later and the car wouldnt unlock with the button on the key so unlocked it the old fashion way.Put the key in the ignition and went to start it but no dash lights etc and the car cranks but wont fire. I plugged it into a snap on ethos i hve and it came up with the fault u0500. Anyone no what the problem is?