ecu swap .............

Are you able to get the error codes?
Do you have some sort of scanner available?

 

P0123 OBD-II Trouble Code: Throttle Pedal Position Sensor/Switch (TPS) A Circuit High Input | YourMechanic Advice

What symptoms were you having with the original ECU installed in the car?

 

For the code, P0123, it might be that the donor ECU you sourced, is bad, or there's a short to ground on the throttle position sensor harness. Check the harness, if you've a dedicated 5volts from the ECU feeding it, and also a good battery ground, with signal voltage that's being fed to the ECU.

If all checks out right, you need to replace that ECU. The ECU isn't sending the required 5volts power to the throttle position sensor.

So you were finally able to get the ECU swapped already? I think you need to reprogram that donor ecu to be in sync with the immobilizer, of your car.
But if you were successful READYING the car, that means the donor ECU worked.

PS:
Do ensure you check the circuitry of the throttle position sensor as per the code displayed.
PSS: If from history, yih hadn't that problem before, my best bet would be the ecu you got is bad.

Replace it, and that's all.

 

I'm afraid, you may have to replace that ecu again, since the old one in your car, wasn't showing that code. It might be that the dedicated circuitry that's responsible for sending signals from the donor ECU to the throttle position sensor is faulty.

Other point is to get someone else to see if they can reprogram the donor ECU to the car, since your locksmith is afraid. I guess, he doesn't know about reprogramming.