Yeah everything goes out just as normal.

You checked the map sensor? May sound draft but that can cause start up issues

At this stage i will try anything. Something is just not getting the battery to give it the power it needs to start

If not map then I can't think what may be. At a push the ecu may be causing issues as in its reading the key but then why turning car over its saying its not valid. But that more than likely be a dealer test

Edit: you checked the leak off pipes. If one is loose (not quite snug) it will let air into the system and cause issues as won't start the car ;-) I've had that problem before. Just push all the clips back in (should be front off engine I would imagine) an try start the car over and see what happens. Can take a few turns of the key if air is still in the system. Easier trying to jump start car why it's being cranked

The car has been remapped, would having to change the battery cause an issue? I know that might sound daft but at a loss here

No remaps won't have anything do with battery I would image. If that was the cause loads people be having issues when need battery.

Well the next obvious issue to check is fuel. Do you have an ODB interface and software? If so check the fuel pressure readings. Possible issues are lift pump in tank, fuel filter, pressure regulator and high pressure pump.
Can you normally hear the lift pump runnning briefly when you turn on? Can you hear it now?
It's time to do some logical fault finding including OBD read fault codes and parameters.
With a freshly charged battery is the engine turning over at the normal speed or is it labouring even then? Labouring with a fresh battery may indicate a mechanical fault such as a "jumped" timing belt.

Robert G8RPI.

Have you checked glow plugs and glow plug relay?

g8rpi said:

Well the next obvious issue to check is fuel. Do you have an ODB interface and software? If so check the fuel pressure readings. Possible issues are lift pump in tank, fuel filter, pressure regulator and high pressure pump.
Can you normally hear the lift pump runnning briefly when you turn on? Can you hear it now?
It's time to do some logical fault finding including OBD read fault codes and parameters.
With a freshly charged battery is the engine turning over at the normal speed or is it labouring even then? Labouring with a fresh battery may indicate a mechanical fault such as a "jumped" timing belt.

Robert G8RPI.

Click to expand...

did you ever try to tow-start the vehicle..??,
if it'll start / at least fire with a tow then it'll help rule out a lot of potential issues;
Basic fuel supply, engine breathing ( compression),
and Immob system

Charlie