No, students typically wouldn't receive bonus marks for incorrect questions in the IISER Aptitude Test (IAT) even if the question was found to be incorrect, and even if they didn't file an objection form.

The IISERs usually don't award bonus marks for incorrect questions. Their primary focus is on evaluating a candidate's understanding and performance based on the correct answers they provide.

Awarding bonus marks for incorrect questions could potentially disrupt the standardized scoring process and create an unfair advantage for some students who might have guessed the wrong answer for the incorrect question. The objection window exists to allow candidates to challenge questions they believe are incorrect. If the IISERs acknowledge a question as flawed, they might consider removing it from the evaluation process altogether. This would benefit all test-takers who attempted that question.

https://engineering.careers360.com/download/sample-papers/iiser-2023-question-paper-answers

I hope it helps!