[talkingcars]

A common cause of problems is wires around the ECU rubbing through, could be that.
Or it could be the earth strap from the gearbox to the slam panel.
It could even be a stray radio impulse that triggered the immboliser.
On my Lada it was the contacts in the ignition switch that had burnt out.
On my scirroco the screw that was used to earth the fuel pump was too small for the hole which caused it not to start, once started it would run all day.