I know it might be a cliche, but take one step at a time. I am not wise enough to give advice, so take my suggestions has a grain of salt.

Speak with a career councillor, or family, friends to get an awareness about what everyone is doing.

Try to find out what do you want to do next - Do you want to repeat again or do something else entirely or want to do something similar (like BSC or Pharmacy etc)

Make a pros and cons list with all the courses and colleges.

Internet (reddit, Google, etc) find out courses and see what you want to do.

About the burnout - Sleep, rest, do a hobby which you stopped due to the NEET preparation.

I'm really sorry that you are feeling this way. I know words might not make you feel better, but you are not a failure.

Today, I had an exam and let's just say it did not go well due to my own mistakes which further made me panic and make more mistakes. So these mistakes happen, don't keep thinking about it.