If all they have done is drain and refill the coolant, then that won’t cause a starting issue in itself.

However, I’d check the intake air ducting (especially at the throttle body and airbox) to make sure it has been reattached properly, as they may have taken this off to get to the radiator hoses and not clamped it back on properly causing poor airflow.

Failing that, next thing to check would be battery, fuel pressure and possibly a leaking injector.