E60 2005. Will not start after a flat battery

[Redarress]

Hi
My car 2005 manual 525 petrol M sport had a flat battery today. Tried jumping it but it would not start so put it on battery conditioner and left for 6hours,
Just tried it again conditioner indicates full charge all lights work could the problem be the immobiliser ?
Battery was changed 4 months ago to try to stop a nearly constant I drive rebooting.

Any pointers would be great

Thanks

[cjj799]

Is the engine cranking when you try to start ?

[Redarress]

No engine is not cranking. When you turn ignition key to start position all dash lights come on correctly

[TWOKWACKS]

Are you sitting in the car with the clutch fully depressed while trying to start the engine?

[Redarress]

Have tried starting cars with clutch in and out...no difference.
Have disconected the intelligent battery sensor but still no joy.

Any ideas please ?

[clockworks]

Why did the battery go flat?

[Redarress]

The IDrive sometimes plays up by keep on rebooting its self and very occasionally stays on when when you switCh the ignition off. My wife drove the car last and said that the IDrive was still on when she shut the door. In the past it has switched off when the alarm is activated but we suspect it did not this time and drained the battery.

[clockworks]

Was just wondering if the flat battery and inability to start were linked to a common cause. Maybe the ignition "switch" is faulty? Could cause the screen to stay on, as well as preventing the engine turning over.

Sounds like a job for an indy with diagnostics.