Our Fabia I (03) was running perfectly normally until the sidelights were left on for a couple of hours the other day. Following morning, it wouldn't start off its own battery, nor on jumpers.

Since then, the AA have failed to diagnose (in admittedly bad weather), the local garage found 1V going to the ECU, has replaced it to no effect, and is now trying to get the timing belt cover off to see if that is slipping. We gather a local electrical mechanic had a look but had no idea.

Does this sound familiar to anyone, and could you please offer any experience to find a solution? Happy to offer a decent bottle of wine to the winning suggestion that leads to a fix!

What engine please, I'm not good at playing guessing games, it's my engineering training.