Take a clue from what Rendon is doing now. I would happy if he turns out to be a left handed Rendon.
For the next week (6 games), just start him once or twice. Use Drury or Sano at 1B. Give Rengifo more starts. Work with him in batting practice and spend more time working with him when he gets back home. If he is still struggling 2 weeks from now, send him down (but not until there is a clear plan and what he needs to work on).