I noticed a couple of posts regarding sirion's failing to start after turning off the engine after a couple of seconds.
My Sirion had a dodgy battery and only just managed to turn the engine over briefly, it just caught and then died,after replacing the battery it refused to start again, I read articles about removing fuses and continually turning over till the engine fires up.
After testing the spark plugs and testing the 3 ignition coils I ran out of ideas.
A fault check came up with no errors and as I didn't know where the injector fuses were and out of frustration I decided to prop the butterfly flap on the intake open, one turn of the key and it came to life ...mad dash to get the flap closed as it was revving like mad!!
It seems ok now and I hope that this info might help others with the same problem.