Candidates will be admitted to IISER only through 

1.KVPY

2.JEE

3.State and Central board channel (SCB)

Eligibility criteria :

JEE CHANNEL -should have category rank within 10,000

SCB CHANNEL - should have passed 10+2 level with science stream with marks equal or above the cutoff percentage in their respective boards and have to appear in the IISER Aptitude Test.

Your mark is too low to apply for IISER through JEE channel. So, give a try through SCB channel and attempt the aptitude test.

All the best..!!