2002 Echo Crank, No Start, No Spark, Immobilizer

[Katooshy]

Hi all

Would appreciate your help in diagnosing my 2002 Toyota Echo NCP10R, manual, 3 door hatch:

- cranks, but will not start
- battery is fine (and headlights etc work)
- fuel pump is fine
- recently serviced (a few weeks ago)
- immobilizer light continues to flash with key in the ignition (tested all three keys);
- engine check light is not coming on at start
- no spark
- fuses and EFI relays all look fine
- have had the car since 04 with no prior trouble
- no modifications of any kind

Car stalled in traffic, started again, went forward 100m and stalled again - now will not start at all.

Mechanic thinks it might be the ECU, but cannot confirm this. Any ideas? Any way to rule out the ECU or confirm that this is an ECU fault?

Many thanks