I have turned myself into an incompetent researcher. I have screwed up my career, now I would like some advice how I can recover?
It is likely that only someone familiar with your field and your portfolio can really help you assess your options. But since you asked for advice, I will offer some observations:

You spent about half your post looking backwards (all the way to undergrad). This is not productive. Instead, look forwards. Where do you want to go? What is the next step?
When considering &quot;where do you want to go,&quot; I recommend you consider all your options. Many people who have never left the university tend to make only superficial inquiries into career options outside of the university.
For a research career, the biggest concrete problem is your poor track record in research. Note, I am assuming that your research record is truly poor as you say, though self-assessment can be very difficult. The academic job market is brutal even for well-qualified candidates, so a poor research record may close some doors, at least temporarily.
I'm not sure what you mean by &quot;I find requirements for...graduate-level coursework. I have none.&quot; I'm very skeptical. In my experience (granted, I'm in the US), it is very unusual for anyone to care about your coursework once you have a PhD. Second, you do have a graduate-level coursework, though you don't think the courses were sufficiently rigorous.
A PhD certifies that you can do research without supervision -- this includes learning new skills. So, your self-studying seems like a good option. Another good option would be to redirect your focus onto areas which are a better match for your interests and skills. Which brings us back to the bolded questions.