Please advise - Small Internships or Certification?

I am currently a penultimate finance students coming from a non target Uni trying to land an intern in IB or Big 4 advisory in my winter break. I have some experience in finance, working in a boutique advisory firm and an Asset Management. However, despite having experience handling end-to-end live model, I feel that my finance fundamental is still weak. Should I take a certification (FMVA by CFI) which will helps me to strengthen my corporate finance fundamentals, or should I try to land an off-cycle internship (most likely in a relatively small VC, since I know someone there). Which one will gives me the best chance of breaking through the industry? Please also tell me what kind of resource should I use to strengthen my fundamental, if you feel that the FMVA certifications is not worth it.

Thanks!