Funny nobody told you that maybe you lack of management skills.
Once, I ended up working with people not being able to code a loop after a year and a half of training. I trained them, until they were able to use a full feature web framework, and it took only one month.
Maybe you should get a training.
Maybe you should read a report about you.
I am not saying that to attack you. Not at all. I understand the problem very well, as I failed to manage teams as well in the past.
But don’t dodge the ball, you are mainly responsible for what’s happening in your team, no matter how much good practice literature you have read in your life.
In that case, stop complaining and get to work. Not as a coder, but as a manager.
Finally, I can be wrong. Maybe you’ve done everything right. In that case, you can, and probably should, resign. Trying to prevent an airplane from crashing with moving your hands is useless, no matter how strong you are. There are plenty of casual teams that will do miracles with your skills to make the best of their’s.