What is the Cal ID of the ROM you're flashing? It sounds like you might be flashing the wrong ROM for your ECU.
Also remember that after flashing, the ECU has to run a few diagnostics when you turn the key on, which will prevent it from starting. It's best to turn the key on and leave it for about 10 seconds before attempting to start the car after a flash. If you try to start it too soon it will just crank and crank without firing until the ECU is done performing its checks.