It's a testing environment, you fixed it pretty quick, and you are the one who set it up initially. I assume your intention is to move fast and get things done, but not prove DB is useless.
If so, people like you are the 'doers' in the team, I doubt any managers will actually blame you for doing too much. Maybe he just gives you some guidence to how to utilize DBA in the future.
Just acknowlege you made a mistake of bringing down the server, not a big deal. You should work with your manager or team on the next step, how to make this procedure more efficient. Maybe build a container based environment and everyone has its own database, etc.
