Dear Reshma, signature and thumb impression are 2 different things all together. If you have been able to correct it during the correction window that means NTA has found it to be a mistake. And if that has been repeated during the correction window as well, NTA will not accept it for the second time as well. We are afraid but the chances of application being cancelled stay high. Please try reaching out to the helpdesk to check if they can do something about it.