I don't say the crew is entirely not to blame, but they it seems as the automation failed first and foremost.
From a layman's perspective, it seems to me that a 'test' flight after major work has been done on the aircraft, must be carried out on the premise that any part of the plane and its systems might be inoperative. The crew was not supposed to believe that the automation would operate correctly - the purpose of the flight was to detect any maintenance-related glitches, including those that affected automation.
They managed to discover just such a glitch, but because they were not prepared for system failure as they should have been, the discovery struck them when they were poorly positioned to recover.
It seems to me that the airline should have deployed proper test pilots, or at least one pilot who could be trusted to follow the manufacturer's SOPs.