Seeking advice regarding networking

I’m a full time credit analyst at one of the top rating agency (S&P/Moody/Fitch) and really wants to break into IBD. But I found that when I cold message people on LinkedIn, out of 100 messages maybe only 5-8 people will reply. I want to seek everyone’s advice on what is the best way to network to get an interview?

• Should I be sending out emails in lieu of LinkedIn? Or maybe send out both?

• During the first conversation, should I bring up a possible referral or follow up later?

I have ex-colleagues who landed IBD offers (not bulge bracket most of them went to boutiques) so I do think it is doable. The question is how to get an interview to begin with, and I realized simply dropping resumes and apply will yield zero result….

I would really appreciate any networking advices given. Thank you all very much.