VW Polo start up trouble

[roy c]

Hi its Roy C's son I have just bought a 2000 vw polo 1.4s and it was fine on the drive back home. I then parked it up and turned the engine off locked it, then I came back about 5 min later and I put the key in the barrel and the ignition lights came on as normal then when I turn it over it started and then immediately cut out I did this multiple times with no luck. I then went out and came back a few hours later and I still wouldn't start I have tried disconnecting the battery to try reset the ecu/immobilizer but no luck. Any advice or past experience to offer thanks Rubes.