ANC uses an array of microphones to sample and create a sound wave that is 90° out-of-phase from the original noise.
Perhaps you damaged one of the microphones used for this process? It could explain why you get garbage microphone input and garbage audio output.
I do recognize that there are many components in the ANC pipeline that may or may not be the cause, but I can't think of many other options at the moment so this outlandish hypothesis is all I have to offer.