I flattened the battery in my newly aquired Signum while cleaning it with the radio on.

Now I managed to bump start it the other day which it did easily. But now it won't start. I've got it hooked up to some jump leads and it's turning over fine, with no nasty noises but it just won't fire.

A couple of times it nearly came to life and made 1000rpm for a second only to die again.

What could be wrong? Crank Shaft Sensor?

The engine management light is on in the dash, but ai can't get a reading with the Torqur app or Carista.

Thanks in advance.