Best summer experiences going into full-time recruiting?

So I'm in my 4th year of a masters program, going into my 5th and final year. I really wanted to land an IBD SA gig for this coming summer, and I had several interviews and superdays, but I didn't come out with any offers.

My question is, what type of experience/internship should I seek out for this summer that will give me the best chances of getting interviews for full-time in the Fall?

Should I look up alumni working at boutiques and send them cold emails? Should I try to find some sort of private wealth management internship? Should I go abroad? Maybe some sort of industry finance internship? Any advice on how I should go about this would be super helpful.

I'm pretty sure doing nothing over the summer would be a nail in the coffin. I go to a target, I have several years of Big 4 internships, an internship at a HF last summer, and good GPA/scores.

I am 100% set on going into banking and won't be giving up; I just don't know what the next step is.

Thanks for any advice, you guys have always been an awesome resource.