Open lightbox when Adblocker is active

If I understand the code correctly, it’s assuming that AdBlocker is switched ON, then does the fetch of the ad. If this is successful, it means the AdBlocker is actually off and displays “Adblock OFF”.

I need to code it the other way around. It shall display “Adblock ON” (alternatively open a lightbox which also works for me with AdBlocker on), if it cannot fetch the ad. Could you help with that?