This is the most comprehensive description of MCAS I've found for the #737MAX https://m.youtube.com/watch?v=L5KQ0g_-qJs
On the engineering side, this should have been caught by testing. Someone explicitly added a 5 second reset timer for MCAS activation without fully understanding if that was correct. Especially from a defensive programming standpoint, the question of what could go wrong == nose pointing down should immediately trigger guardrails. Sadly #boeing only blamed the pilots.