Hello dear student

• Candidates must have qualified B.E/B. Tech or equivalent qualifying degree in first class with an aggregate minimum of 65% marks or CGPA of 6.84 on a scale of 10.
• ISRO is strict about the CGPA or marks and doesn't consider anything less than the given criteria .
• There are no attempts limit in ISRO exam
• Please visit the link for more information.

https://engineering.careers360.com/articles/isro-recruitment

Hope that's helpful

best of luck