We have been having what sounds like a similar problem on a R reg Scenic. PLEASE tell me if this story contradicts your facts & I'll start a new thread.
Normally will start first thing in the morning. But then even after short runs will refuse to start. More speficially ALL electrics seem okay, but on the final turn of the ABSOLUTELY NOTHING! Not even a click from under the bonnet.
Typicall if you give a 20 to 60min rest and try again all will be wonderful.
This has been going on for over a year. Initially very occasional, now seems to be getting much more frequent
I've just had it back from the garage today & nothing on the stored diags and they have no clues. "Perhaps starter motor" but this sounds unlikely to me. I'd expect to hear the solenoid on the motor clicking in. I'd really like to hear from anyone who has any ideas on this one. It is driving the family around the bend. But apart from the problem the machines a goodun. Don't want to have to sell it because of this. But it is VERY TRYING