Corsa 1.2 sxi warm starting problems

[Ebo100]

I've been using my sons Corsa 1.2 sxi this week and when I put petrol in the other night the car wouldn't start on the forecourt. All week the car has been starting from cold first time but this time after a short drive into town and a few stop/starts all I got was a solenoid click. I managed to get is bumped off and drove it straight home. I tried it again on the drive; but again only solenoid click.

My first thought was that a few starts over a short period coupled with the lights etc. had drained the battery and so bought a new one last tonight. I went out to fit it but thought I would try the key first and hey presto it started first try. This has baffled me and leads me to think the battery is not at fault.

Does anyone have any ideas as to what else could be the cause that I can check?

[Ebo100]

well it's happened again tonight, luckily there were loads of students around to flex their muscles

So when the key was turned and held in the start position, the petrol and temp gauges went to zero, but no sign of the lights dimming. After a prolonged period trying to start the warning lights came on the dash, with the spanner symbol flashing. I had my scan gauge plugged in but there were no codes recorded.

Is this pointing to the earth strap or maybe the starter motor?