C5 II 2.0 petrol won't crank

[teuski]

A friend of mine has a weird problem with a EW10A C5 with manual transmission:

When ignition is turned on, lights on dash light up as usual. After about 5 seconds everything else goes off except the engine fault light. Even the multifunction display shuts down.
When tried to start, the starter motor won't run. There's only a faint click of some relay in the BSI. But the starter works fine as i will explain later.
It also stays in economy mode and won't even run the hydraulic pump.

There aren't any significant faults found by Lexia. The ignition lock works (Lexia detects all the positions).
The engine cranks fine when the starter motor solenoid is activated straight from the BSM connector. With the key in starting position the engine still won't start and turns up faults in Lexia from injectors, thermostat etc.
Seems to me the car has no permission to run the starter motor and that's why it turn those faults because the engine is turning when it shouldn't be.

Any ideas? I can't think of any situation where there wouldn't be permission to run the starter motor in a manual transmission C5.

[GiveMeABreak]

First thing to do is a BSI reset. This sounds initially like an electronic problem that the engine is not firing because it hasn't got permission. Normally if the immobiliser is not happy the engine will turn over but it will not start.

So I would check that the battery is in good condition, a weak or failing battery will have an impact on starting the engine up with all the other systems connected up. Next undertake the BSI reset procedure to ensure and rule out any electronic glitches with the ECU.

If the battery terminals have been put on taken off when you've been testing and the BSI procedure has not been followed you may end up with lots of electronic problems. ECU's are very sensitive and if they're not shut down properly, you can store all sorts of electronic problems. Make sure you follow the procedure in full and don't skip any parts. Make sure you put the keys in the ignition after, turn ignition on and hold down lock button for 10 seconds, don't start the car, remove key, operate central locking, then go in and start car and test everything.