Is my AREF damaged?

I wanted to use the 3.3V output on my Mega 2560 for an external reference voltage. I connected the 3.3V output directly to the AREF pin. I included analogReference(EXTERNAL); statement in my sketch and uploaded it to the Mega 2560. However, I may have done an analogRead() before the analogReference(EXTERNAL);

I have since learned elsewhere, that this can possibly damage the Arduino.

Now when I measure the voltage to ground at the AREF, all I read is the 5V Vcc regardless of whether I have set analogReference() to the 1.1V and 2.56V internal reference voltages or to analogReference(EXTERNAL); Do these measurements confirm that the AREF circuit has been damaged? If so, is any other part of the Mega 2560 likely to be damaged? Can I still use the analogReference(DEFAULT) mode?