I would say plenty of both. They obviously had to inform the pilots, but the way the system didn't reset permanently after 2-3 (whatever) sessions of "oh, the pilot trimmed manually, after 10 seconds we keep doing the same thing" was a major major logic blunder. Failure all across the board, if only from the perspective of end-to-end / integration testing if nothing else.
Worryingly, e2e / full integration testing was also the main cause of other Boeing blunders, like the Starliner capsule.
Worryingly, e2e / full integration testing was also the main cause of other Boeing blunders, like the Starliner capsule.