blinking CEL is not for cat damage, it means that catistrophic(sp) engine damage can happen and engine should be turned off asap. It could be a simple misfire, excess knock, slipped timing belt......etc. It is wierd that it didnt leave a stored code.
Now, with the engine OFF and key ON, the blinking CEL is only normal if you have recently disconnected the battery or removed the ASD relay. It means that the ECU has not checked all the perameters of the emission control systems. You will not be able to pass inspection if the cel is blinking with the key on/engine off. It can take a few hundred miles to reset the blinking cel. It will start all over again if you disconnect the battery.