dnr, FWIW, I have recalled tentative conclusions drawn by others in my post no. 1646. Briefly, some ATPL’s thought PF confused the status with overspeed. There are several bits of evidence to support that, though I think it is only a theory, but seems to me the best one at present.
So once fixated upon that, he kept pulling back, presumably trying to pull out of a dive and failing to understand why it wasn’t working.