If someone has cleared JEE Mains with enough marks to get admission in Bachelor's degree into NIT but instead attempts the JEE Advanced Examination and becomes unable to get admission based on JEE Advanced, then it does not mean that he cannot get into NITs now.

He can still sit for Joint Counselling of JEE and get admission into an NIT.

Regards,

Keshav Sahani

No this doesn't happens......if a student scores good in jee mains he can get nit (taking into account that he/she doesn't score goid in jee advanced)...