FL2 Odd electric issue

Elderly gent down the road has a 2010 FL2 (manual) which has stopped behaving. Apparently when he initially gets in and presses the Start button the temp gauge is at maximum but the engine does not turn over. He had already arranged for someone to fit a new battery just in case but that has made no difference.
Just prior to the issues he had been driving it and when stopped at some lights the engine was still running despite the ECO mode set but when he turned down the heating the engine stopped. Turning the heating up again caused the engine to restart.

Any ideas gratefully received although he has bought another FL2 (auto) as he needs transport to get to various clinics etc. If all else fails he will consider selling the 'broken' one but would prefer to get it running again

He needs to get some diagnostic equipment on it to see what is going on.

I believe the heater will override stop start if the battery is failing, assuming the ECM is equipped with stop start functionality.

Nodge68 said:

I believe the heater will override stop start if the battery is failing, assuming the ECM is equipped with stop start functionality.

Click to expand...

Of course, that makes a lot of sense even with my limited knowledge of how power-hungry the FL2 is in it's 'poised' state.

So, time to find a diagnostic unit which I can pretend is for me to be able to do work on my own car