Hi.

From reading the Maharashtra NEET Counselling Rules, a candidate is allotted a seat in 1st round after their registration and then the candidate has the option to accept the seat and then appear in subsequent rounds or not OR candidate forfeits the seat and exit the counselling. Proceedings for 2nd round will depend on your option selection in 1st round. Can you please further clarify what do you mean by " did registration and not participated in the 1st round "?
If you have further queries you can comment as well.

You can read the Maharashtra NEET Counselling rules HERE .