Hi, new member with a 2010 Punto Evo intermittent starting problem, looking for advice/help.

I bought the car privately 2 months ago and it ran fine first few weeks although I did notice the trip computer has been painted over at top and bottom in black paint which I found strange.
3 weeks ago the car would not start after sitting for about 9 hours unused, the lights and dash lights all came on but no central locking or any sign of starting, after about 20 seconds there was a beep from trip computer and yellow petrol light flashes, plenty petrol in it.
Phoned breakdown company who said an isolator switch had been installed, removed it, re-wired it and it started, drove fine.
A week later after sitting overnight again car would not start, same issue, phoned breakdown again who said everything looked fine, eventually removed battery connection and put back and car started, drove fine.
2 days ago after car sat for 2 days unused again it would not start, local garage came and towed it away, had it all day and found nothing wrong but only got it started after removing and putting back battery terminals, they said battery charge and condition perfect.
They recommend taking it to an auto electrician to look at but when I phoned them they said it needs to be non running before they can properly look at it.

This issue is really doing my head in as had to miss appointments and commitments or be late due to the non starting issue.

Would be very grateful if anyone can shed light on what may be wrong.

Thanks in advance!

Do you have a multimeter?

When you have finished with the car for the day ( assuming you got it running ) check the voltage across the battery with ign off and all doors closed. Let the cars electronics go into sleep mode so everything possible is off when measuring the voltage across the battery.

Now leave for a full day and do the same test.

Much difference.

With the aid of an assistant, do the same test whilst trying to start the car, value drops below 10 volts????

With engine running, test voltage across the battery again, and gently increse the engine revs to say 3 k revs, voltage rises to say 14.7 volts??