Amrit, unfortunately you cannot correct the thumb impression right now. The application will remain the way it is and because you haven't re uploaded the thumb impression, the application might be cancelled and you might not even get an admit card.

Hii,

While filling the NEET Application form, one has to follow certain rules guided by National Testing Agency (NTA).  As thumb impression is a Mandatory one. One has to put the thumb impression clearly. Failing to do that may result in not getting Admit card. Hope for the Best.