Need help deciding audit v. IB

Hi all,

I apologize in advance for making any mistakes on this post since its my first one. So I'm a junior at a non-core school and I recently finished an audit internship with a Big 4. I see myself going into investment banking as a career. However, last semester my GPA fell to a cumulative 3.5 so I was a little discouraged and decided to extend my graduation by a year so I could work on my GPA. Other than that, I'm good in the work experience and extra-curriculars aspect. Now I have a full time (and a second internship) offer from the Big 4 I interned at. I'm not sure how much I want to do the full time but it would be nice to have another internship with them since I have one more summer before I apply to the IB's interview process. The problem is - my second internship is contingent upon me signing a full-time offer with the firm. I would like to clarify that I am an international student and finance internships are hard to come by for international students. Do you think I should (1) take up the risk of letting go of this offer (and thus the second internship) and continue finding a finance internship for next summer or (2) should I take up this internship and towards the end tell them I won't be coming back for a full time (which would be my least preferred option considering how unprofessional it is and would result in burning bridges with them) or (3) take up this audit internship and switch to IB a few years later into my career considering I don't have a guarantee for an IB internship. What do my chances look like? Also, one more thing I'd like to add is that I tried to request an internal switch to the firm's TS or FAS practice for my second internship but that didn't work out. I don't want to end up in a situation where I end up burning bridges with the firm and not even have an IB internship and have to go back to my country without a job. I'd appreciate any guidance. Thanks!