HELP!!! No Junior Year summer internship.....BUT Co-founder startup experience over the summer

NOTE: This is my first post on WSO.

Background: International student, rising senior at Top 50 business school in Boston.

Stats: 3.4 GPA, c-suite leadership positions in school and 2 summer internships in Financial services with relevant experience in Market research, valuation, advising C-level people and giving them recommendations on investments.

Hello everyone,

I'm an international student and rising senior at a Top 50 school in Boston which is Non-target for MBB and several Tier 2 firms (think strategy&, OW, LEK, Deloitte Consulting etc) but is a target for some of the Big 4 for advisory roles. I'm very interested in breaking into these top firms (Both MBB and Tier 2 firms) for FT role in an international office (think Europe, Canada, Asia etc) but am having some issues positioning myself in the best possible manner. I am also looking at the Big 4 and small boutique consulting firms.

At the moment, I was looking to get advice on two things:

1) I'm still looking for a junior year internship....BUT I have an opportunity to start a startup over the summer and work over it. While I'm doing this over the summer, should I still continue looking for a junior year internship? I was looking at other startups/ returning back to what I was doing earlier in financial services.
What impact would this have on recruitment?

2) What else should I do to bolster my chances of landing offers at these top firms?

Any input or advice would be really appreciated! Looking forward to any responses!