Skoda Octavia. No engine warning symbol, won't start

[robinessex]

Can any one help. Son in laws Skoda Octavia stopped on his way to work. I went out to it to await the AA. Car wouldn't start, spun over ok, seems like no spark. Then, suddenly, when I turned the ignition key on, the engine warning symbol came on. It hadn't been coming on previously, which I hadn't noticed, but ALL the other warning symbols had been present. The car started up ok. The AA guy arrived, run a diagnostics, couldn't find any errors. Son in law drove home from station that evening (3 miles) ok. Went to station next morning, stopped at ticket machine, car wouldn't re start. Called AA again, diagnostics plugged, lots of gawping at the screen, and then suddenly the light appears again, and it starts. Since had a full diagnostics done, the guy suggested the ECU was not getting power intermittently. A few faults showed up, abs, emissions, and some of the check parameters had been purged, which is why he suggested ECU power supply failure. Anyone any ideas ?